
Class QD,: 
Book. ,-Jfr 
Copyright^? 



COFVKSGHT DEPOSrT. 



JL% 



A TEXT-BOOK OF CHEMISTRY 



JONES 



TEXT-BOOK OF CHEMISTRY 



FOR THE USE OF 



STUDENTS AND PRACTITIONERS OF 
MEDICINE, DENTISTRY AND PHARMACY 



BY 

WILLIAM RUSSELL JONES, M.D., Ph.G. 

PROFESSOR OF MEDICAL CHEMISTRY AND TOXICOLOGY, AND LECTURER ON MEDICAL DIAGNOSIS IN 

THE UNIVERSITY COLLEGE OF MEDICINE; VISITING PHYSICIAN TO THE VIRGINIA 

HOSPITAL. RICHMOND, VIRGINIA 



•ffllusttatefc 



PHILADELPHIA 
P. BLAKISTON'S SON & CO 

IOI2 WALNUT STREET 
I905 



URRARYot SONQResiJ 
fwo Oop«es rtecttvet | 

SEP. 12 190* 
' 6L ISA b« 

COPV 6* 



31 



Copyright, 1905, by P. Blakiston's Son & Co. 



Press of 

The New Era Printing Company, 

Lancaster, Pa, 



TO THE MEMORY OF MY GRANDFATHER 

DOCTOR JAMES LAWRENCE JONES 

WHOSE EXEMPLARY CHARACTER AND ENNOBLING PRECEPT, WHOSE SCHOLARLY 

ATTAINMENTS AND SKILL AS A PHYSICIAN, HAVE EVER BEEN 

SOURCES OF INSPIRATION TO THE AUTHOR 

THIS VOLUME IS 
RESPECTFULLY AND AFFECTIONATELY INSCRIBED 



PREFACE. 



In this volume the author has endeavored to include all that 
is needed in chemistry for students of medicine, dentistry and 
pharmacy, and, at the same time, care has been exercised to 
avoid the introduction of unnecessary material. 

The text is based upon a system of teaching which has been 
successfully followed for nine years ; and the subject is pre- 
sented in an inductive manner, commencing with simple state- 
ments and avoiding technical terms, until the student has 
begun to acquire familiarity with his work. 

The atomic weights used are those adopted in the United 
States Pharmacopoeia, Eighth Decennial Revision, taken from 
the report of the International Committee on Atomic Weights 
for 1904, and are given in a table in the body of the book. In 
the description of each element the atomic weight is given in 
the nearest approximate whole number to that expressed in 
the table. 

The references to the United States Pharmacopoeia are based 
upon the eighth decennial revision, to which this book is made 
to conform in regard to official preparations and chemicals. 
The expressions of specific gravity and solubility are based 
upon the new standard of temperature, as adopted by the Phar- 
macopoeia, viz., 25 ° C, 77 F. All statements of temperature, 
unless otherwise specified, are given in terms of the centigrade 
scale. 

The author has not seen fit to depart from the present 
system of orthography by the introduction of such words as 
chlorin, bromin, sulfid, morphin, glucosid, etc., believing that 
such a system, if rigidly applied, would lead to the formation 



Vlll PREFACE 

of undesirable terms, and would interfere with the classifica- 
tion of many active medicinal agents, such as the alkaloids 
and glucosides. 

The writer is indebted for material to many authors, and 
especially to the following: Bartley, Remsen, Simon, Ogden, 
Vaughan and Novy, Rockwood, Bunge, Brubaker and 
Heitzmann. 

The drawings for illustrations were furnished by Dr. John 
W. Broadnax and the section on urinary concretions and 
sediments was furnished by Dr. E. G. Hopkins; to both of 
these gentlemen the author wishes to express his most grateful 
thanks. 

June 30, 1905. 



CONTENTS. 



Introduction . i 

Properties of Matter . 2 

General Properties of Matter 2 

Specific Properties of Matter ........ 5 

PART I. 

Physics . • 7 

Energy 7 

Cohesion 8 

Adhesion 8 

Gravitation 11 

Density and Specific Gravity 15 

Physical Constitution of Gases 20 

Heat 24 

Physical Effects of Heat upon Matter ... 24 

Transmission of Heat .30 

Specific Heat 32 

Latent Heat 33 

Light . 38 

Electrical Energy 50 

Magnetism . . . 50 

Electricity 51 

Electricity by Friction • . . . . 52 
Electricity by Chemical Action .... 53 
Electricity by Magnetic Induction ... 55 
Heating, Lighting and Chemical Action of Elec- 
tricity 58 

Electrical Units 61 

PART II. 

Chemical Philosophy . , 63 

Distinction between Physical and Chemical Action . . 63 

Elements and Compounds 64 

Laws Governing Chemical Action 65 

The Atomic Theory . . . . . . . . 67 

ix 



X CONTENTS 

Molecular Constitution of Gases 68 

Atomic Weight 70 

Quantivalence, Atomicity, or Valence 71 

Chemical Symbols and Equations 72 

Methods of Determining Atomic and Molecular Weights . 76 

Conditions Influencing Chemical Changes .... 80 

Nomenclature . . . . 82 

Classification of Compounds 83 

The Elements 85 

Classification of Elements 86 

PART III. 

Inorganic Chemistry 91 

The Non-Metallic Elements . 91 

Hydrogen . 91 

Oxygen 94 

Ozone 96 

Compounds of Oxygen with Hydrogen ... 96 

Water 97 

Hydrogen Peroxide . . . ... 99 

Nitrogen 100 

Compounds of Nitrogen with Hydrogen — Ammonia 102 

Compounds of Nitrogen with Oxygen . . . 104 

Carbon 109 

Compounds of Carbon with Hydrogen . . . no 
Compounds of Carbon with Oxygen . . .112 

Silicon 115 

Boron . . . 116 

Sulphur 117 

Compounds of Sulphur with Hydrogen . . . 119 

Compounds of Sulphur with Oxygen . . . 120 

Phosphorus 126 

Compounds of Phosphorus with Hydrogen . . 129 

Compounds of Phosphorus with Oxygen . . 129 

The Halogens 133 

Chlorine 134 

The Oxides and Oxygen Acids of Chlorine . . 138 

Bromine 140 

Iodine 142 

Fluorine -. 145 

The Metallic Elements . . 149 

Alkali Metals 151 



CONTENTS * XI 

Potassium 151 

Compounds of Potassium . . . ' . . 153 

Sodium 158 

Compounds of Sodium ..... 159 

Lithium 163 

Ammonium 164 

Analytical Reactions 168 

Magnesium Group 170 

Magnesium 170 

Beryllium 173 

Alkaline Earth Metals 173 

Calcium . 174 

Compounds of Calcium 174 

Strontium . . ' . 178 

Barium . 179 

Radium 181 

Analytical Reactions 183 

The Earth Metals . . . . . . . . 184 

Aluminum 184 

Cerium 188 

Metals of the Iron Group 188 

Iron 189 

Halogen Salts of Iron 191 

Iron Sulphur Compounds 191 

Oxygen Salts of Iron . . . . . 192 

Manganese 195 

Basic Oxides of Manganese .... 196 

Acid Oxides of Manganese .... 197 

Chromium 198 

Basic Oxides of Chromium .... 199 

Acid Oxide of Chromium 199 

Cobalt 201 

Nickel 202 

Zinc 202 

Analytical Reactions 205 

Metals of the Lead Group 206 

Lead 206 

Copper 209 

Bismuth . . 211 

Silver 214 

Mercury 216 

Compounds of Mercury 218 

Cadmium . . . . . "• . . . . 223 



Xll CONTENTS 

Analytical Reactions 223 

Metals of the Arsenic Group 224 

Arsenic 224 

Oxides and Acids of Arsenic .... 226 

Antimony 232 

Compounds of Antimony with Sulphur . . 233 

Tin . . . . . . . . . . 235 

Gold . 235 

Platinum 237 

Molybdenum 238 

Tabular Scheme for Analysis 239 

PART IV. 

Organic Chemistry . . 241 

General Considerations ^ 241 

Classification of Organic Bodies . . . . . . 258 

Hydrocarbons 260 

The Paraffine or Methane Series of Hydrocarbons . 262 

The Olefine Series of Hydrocarbons . . . . 267 

The Acetylene Series of Hydrocarbons .... 269 

Halogen Derivatives of Hydrocarbons .... 270 

Alcohols 273 

Aldehydes . 278 

Ketones 282 

Organic Acids 283 

Ethers and Compound Ethers, or Esters .... 295 

The Natural Fats . 298 

Carbohydrates, or Saccharids . 301 

Glucosides 314 

Nitrogenous Bodies of Simple Structure . . . . 316 

Amines and Amides 317 

Cyanogen 320 

Aromatic Hydrocarbons, or Benzene Series .... 326 

Benzene Series 328 

Terpenes . . 330 

Phenols and Phenol Derivatives 333 

Nitrogen Compounds of Benzene 338 

Amido Derivatives of Benzene . . . .'•'". 340 

Compounds with Condensed Benzene Nuclei . . . 344 

Compounds Containing Nitrogen in the Benzene Nucleus 347 

Alkaloids 350 

Liquid Volatile Alkaloids . 352 

Solid Non- Volatile Alkaloids . . . . . . 352 



CONTENTS - Xlll 

Ptomaines . . . 357 

Leucomaines . . . ... . . . . . 360 

Toxines and Antitoxines . . . . . A . 362 

Proteids - . 363 

Classification of Proteids 366 

PART V. 

Methods of Quantitative Analysis 371 

The Gravimetric Method 371 

The Volumetric Method ■ . 374 

Calculation of Results 376 

PART VI. 

Physiological Chemistry 379 

Introduction . . 379 

Relation between Plant and Animal Life .... 380 

Chemical Composition of the Human Body .... 382 

Digestion . . • 394 

Respiration . 403 

Milk 405 

The Urine . . . ' 407 

Physical Properties 409 

Normal Constituents 413 

Abnormal Constituents 423 

Urinary Concretions . . . . . . . 431 

Urinary Sediments 433 

Index 449 



A TEXT-BOOK OF CHEMISTRY, 



INTRODUCTION. 

Chemistry has for its object a study of the essential nature 
and properties of matter, the changes of constitution which 
matter undergoes, and the laws relating to these changes. It 
is concerned with modifications in structure, and changes occur- 
ring in constitution, whether by union or separation, of the 
various forms of matter; and it also includes an investigation 
of the rules, or laws, which are constantly in action to produce 
these changes. In studying the essential nature of matter, 
chemistry furnishes the method of inquiry in relation to its 
composition, its internal structure, and its ultimate character. 
Chemistry also considers the properties of matter, or its peculiar 
qualities, by which we may recognize its different forms, and 
its suitability for utilization in different ways. 

This science finds abundant application in the art of medi- 
cine and the associated professions of pharmacy and dentistry; 
it furnishes the methods for obtaining the medicinal agents 
which are used in the treatment of disease, and the sub- 
stances which are employed for the preservation of health; 
it gives information in reference to the substances used as 
articles of food, and a warning and means of protection against 
those which act as poisons ; it gives information in regard to 
the composition of the body, and in reference to changes taking 
place in the tissues; and it affords a means by which we may 
recognize the presence of disease. 

A branch of science which is directed to the study of matter, 
or the material substance of which the universe is composed, 

2 I 



2 TEXT-BOOK OF CHEMISTRY 

may seem too extensive for inclusion in one department of 
human knowledge, but a close investigation of the great num- 
ber of bodies presented to our senses will reveal the fact that 
they are made up of a comparatively small number of simple 
or elementary substances. These simple, elementary forms of 
matter, by their existence in various modifications and com- 
binations, produce the endless array of materials with which 
we are familiar. 

The changes which are constantly taking place in nature, 
such as the disintegration of rocks or the evaporation of water, 
are known as phenomena, and a study of these changes will 
clearly show that they consist of two kinds, viz : Those which 
result in an entire change in the nature of substances, such as 
are produced by combustion; and those which are of a tem- 
porary or less serious character, such as the formation of ice. 
These two classes of phenomena are studied in the sciences of 
chemistry and physics, but since the phenomena are so closely 
associated in nature the sciences are incapable of complete 
separation. It is for these reasons that the subject of physics 
will be given a brief consideration after we have directed our 
attention in a general way to a study of the properties of matter. 

PROPERTIES OF MATTER. 

Matter is anything that occupies space, and that is revealed 
to our senses by its properties. For convenience of study, 
the properties of matter may be divided into two classes. This 
division embraces a consideration of the General Properties of 
matter, on the one hand, and the Specific Properties of matter, 
on the other. 

GENERAL PROPERTIES OF MATTER. 

The general properties of matter are those properties which 
pertain to all forms of matter. They are, extension, divisi- 
bility, compressibility, porosity, inertia and indestructibility. 



PROPERTIES OF MATTER 3 

Extension, or Figure, is a term used to express the fact 
that all matter occupies space; that is, it has length, breadth 
and thickness. This being true, every piece of matter has its 
boundaries, and the quantity of matter residing within these 
boundaries is called mass. 

Divisibility is the property in virtue of which matter is 
capable of being divided. A substance may be ground to a 
powder so fine that the particles are invisible to the unaided 
eye, but these particles, when viewed under the microscope, 
will appear large and irregular. Further subdivision may be 
accomplished by dissolving the substance in a liquid — a grain 
of strychnine will impart a bitter taste to a barrel of water, and 
the particles of strychnine which give rise to the bitter taste 
in a drop of this water must be of exceeding smallness. Sub- 
division even greater than this may be accomplished by chemi- 
cal change, and further division may still occur as a result of 
the action of electrical energy in vacuum tubes, or in the emana- 
tions from radium. See radium, page 181. 

Compressibility is the property by which matter may be 
caused to occupy less space. If we apply pressure to a gas, the 
volume will be thereby lessened ; and, in like manner, the volume 
of a liquid or solid may be reduced by pressure. Seeing that all 
matter is compressible, we have to conclude that it does not 
completely fill all the space within its boundaries. 

Porosity is the property of having spaces or pores between 
the particles of which matter is composed. This property is 
at once suggested to the mind by the fact that all matter is 
compressible. These spaces can be clearly seen by the un- 
aided eye in some substances of an extremely porous charac- 
ter, such as charcoal and cork : in other bodies they are in no 
wise visible, even with the aid of the most powerful micro- 
scope; yet we know that apparently dense substances are 
porous, for gases, and even liquids, may be forced through 



4 TEXT-BOOK OF CHEMISTRY 

them by means of powerful pressure. Thus it is that matter 
has an internal as well as an external surface. The internal 
surface is that surface which goes to make up the pores or 
spaces between the particles, while the external surface is that 
which bounds the mass. 

Molecules. In assuming that matter is porous, and in 
assuming that spaces lie within its boundaries, we must at 
the same time assume that matter is composed of small par- 
ticles, between and among which these spaces reside. In fact, 
it is impossible for us to conceive of the internal nature of 
matter in more than two ways, and these are, that matter is 
either homogeneous throughout and occupies all the space 
within its boundaries, or that it is made up of small particles 
and does not completely fill this space. The properties of 
porosity and compressibility point to the belief that matter is 
made up of small particles, and these small particles are called 
molecules. Molecules may be defined as the smallest particles 
of matter that have separate existence. The molecules of a 
body are not in absolute contact, and the spaces intervening 
between them are called intermolecular spaces. Furthermore, 
the molecules are known to be in a constant state of vibration. 

All matter is found in one of three states of aggregation: 
it is found in the solid, the liquid, or the gaseous state. 1 Some 
substances occur only as solids ; others occur as solids or 
liquids ; and some can be obtained in the solid, liquid or gaseous 
state, under varying conditions. 

In solid bodies, the molecules occupy fixed positions in re- 
lation to each other, and the form of the body cannot be 
changed without the application of force. 

In liquids, the molecules are free to glide upon each other 

1 A fourth form of matter is believed to exist in the emanations from 
radium, and in the " cathode rays " of an electrical discharge through a 
vacuum tube. This is known as the ultra-gaseous or corpuscular form 
of matter, and is believed to consist of subdivided atoms. 



PROPERTIES OF MATTER 5 

and to change their relative positions, so that the body is 
mobile and accommodates its shape to that of the containing 
vessel. 

In gases, the molecules not only glide upon each other but 
have a tendency to advance in straight lines, and thus tend to 
increase the volume of the body. 

Inertia is the property of matter in virtue of which it cannot, 
of itself, change its condition. In whatever condition matter 
happens to be placed, it must remain in that condition until 
force be applied to produce a change. 

Indestructibility. Matter cannot be destroyed. We may 
tear, rend or grind a substance, but we cannot lessen the 
quantity of matter which it represents. Fire is considered 
the most destructive of all agents, but it is not capable of de- 
stroying matter; for if we burn a substance, and examine the 
products of combustion we invariably find in them all the 
matter which was contained in the body burned. Matter may 
be changed but not destroyed. 

SPECIFIC PROPERTIES OF MATTER. 

Specific properties are the properties presented by certain 
definite bodies. We say of silver, a definite body, that it is a 
white, shining, malleable, ductile solid, all of which terms are 
expressive of specific properties. The specific properties 
worthy of special mention are, tenacity, ductility, malleability, 
hardness, transparency, translucency, opacity, color, odor and 
taste. 

Tenacity. When a body shows great resistance to the sepa- 
ration of its parts it is said to be tenacious. 

Ductility is the capability of changing form by action of 
traction or pressure. This property is exhibited in those bodies 
which may be drawn out in the form of wire, and it is highly 
developed in the metals, gold, silver and platinum. 



6 TEXT-BOOK OF CHEMISTRY 

Malleability is the property of being reducible to thin leaves 
by hammering or by passing between rollers. Gold is the most 
malleable of the metals, being reducible to i/256,oooth of an 
inch in thickness. 

Hardness is the resistance which a substance opposes to 
being scratched or penetrated. The relative hardness of two 
bodies is determined by ascertaining which of the two will 
scratch the other. 

Transparency is the property of allowing the free passage 
of light. Objects may be seen through transparent bodies. 

Translucency is the property of allowing some light to pass 
through, but objects cannot be seen through translucent bodies. 

Opacity. Opaque substances obstruct the passage of light 
to a greater or less degree. 



PART I 



PHYSICS. 

Before entering upon a detailed study of the chemical rela- 
tions of matter it is desirable to give a brief sketch of certain 
branches of physical science, the study of which is necessary 
to an understanding of chemical methods and reactions. 

Physics, as distinguished from chemistry, is chiefly concerned 
with the study of energy. The changes taking place in matter 
which do not affect its essential nature are physical changes, 
and a study of the forms of energy producing these changes 
is embraced in the science of physics. 

ENERGY. 

Energy is made manifest to the senses by the effect it pro- 
duces upon matter ;-^-as the falling of a body to the earth, or 
heating a platinum wire by the passage of an electrical current. 
With the expenditure of energy a corresponding change is 
produced upon matter, and the production of this change is 
called work. 

Potential Energy is energy stored up. A stone held some 
distance from the surface of the earth contains potential energy 
on account of its position, for when its support is removed 
the stone falls to the earth, thus making the energy manifest. 
A wound watch spring contains potential energy, on account 
of its condition of tension. 

Kinetic Energy is energy in action, and is seen in the fall- 
ing stone, or in the rapidly unwinding watch spring. 

7 



8 TEXT-BOOK OF CHEMISTRY 

The forms of energy of interest to the student of chemistry 
are cohesion, adhesion, gravitation, heat, light and electricity. 

Cohesion is the force of attraction exerted between similar 
kinds of molecules, and holds the particles of matter together 
in the form of mass. Cohesion is very strongly exerted be- 
tween the molecules of solid bodies, and causes their mass to 
preserve a definite form. In the case of liquids cohesion is 
more feebly exerted, and in gases it seems to be suspended. 

Adhesion, or Surface Action is the attraction exerted be- 
tween the molecules upon the surfaces of bodies in contact. 
This form of attraction takes place between the molecules 
upon the external surfaces of bodies, as shown by pressing two 
plates of glass firmly together, when they will adhere, or 
stick; it also takes place between the molecules upon the in- 
ternal surfaces of bodies, as shown by dissolving solid bodies 
in liquids, or by the absorption of gases by charcoal. 

Most solid bodies when dipped into a vessel of water are 
made wet, and this wetting is due to the fact that adhesion 
between the molecules of the solid and the liquid is sufficiently 
strong to overcome the force of cohesion between the molecules 
of water. In some instances a liquid does not wet a solid, as 
is seen in the case of a glass rod dipped into a vessel of mer- 
cury: in this case the force of adhesion is too feeble to over- 
come cohesion. 

The surface of a liquid contained in a narrow vessel always 
shows a concave appearance when adhesion is exerted between 
the liquid and the sides of the container. It is for this reason 
that the surface of water contained in a small glass tube pre- 
sents a higher level at its circumference than at its center. 
The curved surface so formed is called a meniscus, and, in 
reading the level of the liquid in measuring, either the center 
or circumference of the curved surface has to be selected. A 
further manifestation of adhesion is shown when capillary 



ENERGY 9 

glass tubes are dipped into a vessel of water : in this case the 
level of the water in the tubes will be higher than the level 
of the water on the outside. This action is known as capil- 
lary attraction. The extent to which capillary attraction is 
exerted depends upon the nature of the liquid, the temperature, 
and the diameter of the tube ; it is inversely proportional to the 
diameter of the tube, and it is lessened by the action of heat. 
Where a liquid does not wet a solid there is capillary depres- 
sion instead of elevation, and the surface of the liquid is convex 
instead of concave. 

Adhesion between solids and gases is indicated by the fact 
that solid bodies weigh less when hot than when cold. Solids 



Fig. 



Fig. 




Capillary Attraction. 



Capillary Depression. 



have atmospheric gases adhering to the surface, which are 
driven off by heat. Adhesion between liquids and gases is indi- 
cated by the solution of gases in water. In some cases the 
solubility is very great. Solution is favored by the action of 
pressure and the abstraction of heat. 

Diffusion means the intermingling or mixing of masses of 
gases or liquids by the motion of their molecules. This mixing 
may take place when the gases or liquids are placed in direct 
contact, or when a porous substance intervenes between them. 
If we place some water in the bottom of a test-tube and then 



IO 



TEXT-BOOK OF CHEMISTRY 



carefully pour a little alcohol upon its surface, in such manner 
that the alcohol and water form separate layers, and then allow 
the tube to stand for some time, it will be found that the alcohol 
and water gradually intermingle their particles and ultimately 
become thoroughly mixed. If a porous diaphragm of clay 
or animal membrane be interposed between the two liquids they 
will mix through the pores of these substances. 

Fig. 3. 




Dialyzer. (After Rockwood.) 

Gaseous bodies brought together in the same way will thor- 
oughly mix with each other. The rate of diffusion of gases 
through porous diaphragms takes place in a regular or uni- 
form manner, and this fact is expressed in the law of Gra- 
ham, which says : The velocity of diffusion of a gas is in- 
versely proportional to the square root of the density. The 



GRAVITATION I I 

square root of the density of oxygen being four and that of 
hydrogen being one, the velocity of diffusion of hydrogen 
would be four times greater than that of oxygen. 

Dialysis, or Osmosis. The investigations of Graham led 
to the discovery that certain solid bodies held in solution are 
capable of diffusing through porous membranes, such as parch- 
ment or bladder, while certain other bodies do not possess 
this property. The substances which thus diffuse are always 
crystallizable, while those which do not diffuse cannot be 
crystallized. He named the diffusible bodies, crystalloids, and 
the non-diffusible bodies, colloids. These phenomena are re- 
ferred to in the terms, dialysis, or osmosis, and they are in- 
vestigated by means of the dialyzer. 

The dialyzer consists of a glass cylinder open at both ends, 
over one end of which is tied a membrane of parchment or 
bladder, which is placed in contact with water contained in 
another vessel of larger size. The liquid to be dialyzed is 
placed upon the porous membrane in the smaller vessel, and 
this, in turn, is placed upon water contained in the larger 
vessel. Solutions of crystalloids will pass from the inner ves- 
sel to the water in the outer vessel, and at the same time water 
passes in the opposite direction. 

GRAVITATION. 

Gravitation is the force of attraction exerted between masses 
of matter. It is a universal property of all masses of matter 
that they tend incessantly to approach each other, whether at 
rest or in motion ; whether near together or separated by great 
distances. The force of gravitation holds the planetary bodies 
in position in the universe; it causes a stone to fall to the 
earth's surface. The force of attraction of gravitation between 
two * bodies is directly proportional to the product of their 
masses, and inversely proportional to the square of the dis- 
tance between them. 



12 



TEXT-BOOK OF CHEMISTRY 



Fig. 4. 



Terrestrial gravitation is shown in the tendency of bodies 
to fall to the earth's surface, and the direction taken by a falling 
body is called a vertical line. The vertical is determined by 
means of a plumb line, which consists of a weight tied to the 
end of a string and suspended by its free end, A line or plane 
drawn at right angles to the vertical is said to be horizontal. 
The surface of a liquid at rest always assumes the horizontal 
plane. 

The center of gravity of a body .is that point through which 
passes the resultant of the forces of attraction between the 

body and the earth. This point, 
in the case of a sphere of uni- 
form density, is at its center; but, 
in the case of a body of irregular 
shape or of varying density, it 
may be found at a point some 
distance from the center, or even 
outside of the body. The center 
of gravity may be determined by 
suspending a body by means of 
a string in two different posi- 
tions, and extending the line of 
suspension in each case; the point 
in the body at which the two lines intersect is the center of 
gravity. 

Weight is an expression denoting the amount of attraction 
of the earth for the body weighed, as compared to that of a 
standard. It leaves out of consideration the attraction of the 
substance for the earth, which is so infinitely small that it can 
he disregarded. 

The balance is the instrument generally employed for meas- 
uring weight. The instrument in its simplest form consists of 
a beam suspended at a point directly over the center of gravity 




Method of Finding Center of 
Gravity. 



GRAVITATION 



13 



so that in oscillating it tends to assume a horizontal position. 
From a point near each extremity of this beam a scale pan is 

Fig. 5. 




Balance. (After Coblentz.) 
Fig. 6. 



S r 




© 



Balance. (After Coblentz.) 

suspended, in one of which the standard weight is placed and 
in the other the substance to be weighed. The axes of suspen- 
sion of the balance consist of prisms whose sharp edges rest 



14 TEXT-BOOK OF CHEMISTRY 

upon supports of agate, in order to reduce the amount of fric- 
tion to a minimum degree. 

Systems of Weights and Measures. The standards for 
weighing and measuring at present in use in this country are 
the English, and the French, or Decimal. 

The English System of Weights and Measures consists of : 

Apothecaries' Weight. 
20 Grains (gr.) = i Scruple. 

3 Scruples (3) = i Drachm. 

8 Drachms (3) = I Ounce. 
12 Ounces (5) = i Pound (lb). 

Wine, or Fluid Measure. 
6o Minims (Min.) = i Fluid Drachm. 

8 Fluid Drachms (f3) = i Fluid Ounce. 
16 Fluid Ounces (fj) = i Pint. 

8 Pints (0) = i Gallon (Cong.) 

Measures of Length. 
12 Inches (in.) = i Foot. 
3 Feet (ft.) = I Yard (yd.) 

The Imperial Gallon of the British Pharmacopoeia contains 
160 fluid ounces, 277.274 cubic inches, or 70,000 grains. The 
Imperial Pint contains 20 fluid ounces, 34.659 cubic inches, or 
8,750 grains. Corresponding measures of the United States 
Pharmacopoeia are somewhat different from these standards; 
the gallon containing 231 cubic inches, 128 fluid ounces, or 
58,372.2 grains ; and the pint containing 16 fluid ounces, 28.875 
cubic inches, or 7,296.525 grains. 

The French, Metric, or Decimal System of Weights and 
Measures. The unit of this system is the Meter, which is the 
length of a platinum bar kept in the public archives of France. 
The length of this bar is equal to one forty-millionth part of 
the circumference of the earth through the poles. 

The Meter is employed as the unit for measuring length, and 
its equivalent in the English system to 39.37 inches. 



DENSITY AND SPECIFIC GRAVITY ' I 5 

The Liter is the unit of capacity, and is employed for measur- 
ing volume. It is obtained by taking the cubic contents of one- 
tenth of the meter — a cubic decimeter — and contains one thou- 
sand cubic centimeters. Its equivalent in the English system 
is 33.81 fluid ounces. 

The Gram is the unit of weight, and is obtained by taking the 
weight of a cubic centimeter of water at 4 degrees Centigrade, 
which is the temperature of greatest density of water. The 
equivalent of the gram in the English system is about 15.43 
grains. 

The ratio of increase and decrease of these several units is 
decimal, and for this reason the system is sometimes called the 
decimal system. Multiples of the units are indicated by using 
the Greek prefixes, Deka, ten; Hecto, one hundred; Kilo, one 
thousand. Sub-multiples are indicated by using the Latin pre- 
fixes, Deci, one-tenth; Centi, one-hundredth; Milli, one-thou- 
sandth. 

Table of Metric Weights and Measures. 

Kilo 1000. 

Hecto . 100. 

Deka 10. 

Meter. Liter. Gram. 

Deci 1/10. 

Centi 1/100. 

Milli 1/1000. 

DENSITY AND SPECIFIC GRAVITY. 

The expression density is a term used to denote the mass or 
quantity of matter contained in a body compared with the 
quantity of matter contained in a standard body of equal vol- 
ume. Specific gravity is a term used to express the relative 
weights of two bodies of equal volume, one of which is taken 
as the unit of comparison. Perfectly pure water, at the tem- 
perature of 25 ° C. or yy° F., U. S. P. 1900, is taken as the 
standard in expressing the specific gravity of solids and liquids : 



1 6 TEXT-BOOK OF CHEMISTRY 

in the case of gases, air is used as the standard. While air is 
used as the standard of comparison in speaking of the specific 
gravity of gases, their density is expressed in terms which refer 
to hydrogen. A gas is said to have specific gravity as referred 
to air, and density as referred to hydrogen. 

The specific gravity of a body is expressed by using a num- 
ber which shows how many times the weight of a given volume 
of water is contained in the weight of an equal volume of the 
substance. Such a number will be greater or less than unity, 
as the substance in question is heavier or lighter than water. 

Methods of Determining Specific Gravity. In all deter- 
minations of specific gravity the essential problems to be solved 
consist in finding and weighing equal volumes of the substance, 
and of the standard body; the weight of the substance is then 
divided by the weight of equal volume of standard, and the 
quotient expresses the specific gravity. 

In Liquids, the specific gravity is easily found because of the 
simplicity of the methods required to find and weigh equal 
volumes. The method here consists in selecting a glass flask 
with a narrow neck and accurately balancing it upon the scales 
with a counterpoise of equal weight. Distilled water at a tem- 
perature of 25 ° C. is poured into the vessel until it contains 
exactly 1000 grains, and a mark is made on the neck of the flask 
at the level of the liquid. When this is finished the vessel is 
emptied of water and dried, and the liquid whose specific 
gravity it is desired to find is poured into the vessel until its 
level reaches the mark on the neck. This is then placed upon 
the scales and weighed, the counterpoise being retained to bal- 
ance the weight of the empty flask. The weight of this liquid, 
which corresponds in volume to 1000 grains of water, is divided 
by the weight of the water — 1000 grains. The quotient ex- 
presses the specific gravity. 



DENSITY AND SPECIFIC GRAVITY \J 

Example : 
Required, to find the specific gravity of sulphuric acid. 

Weight of an empty glass flask ioo grains. 

Weight of flask filled with water 1,100 grains. 

Weight of water 1,000 grains. 

Weight of flask filled with sulphuric acid 1,940 grains. 

Weight of flask ioo grains. 

Weight of acid 1,840 grains. 

1,840 -h 1,000 = 1.840, specific gravity of the acid. 

In Solids, the determination of specific gravity involves the 
same principles as above, but the methods are different. The 
specific gravity bottle is filled with water and weighed; then 
the solid is weighed separately. These two weights are added 
together, and the sum denotes the weight of the bottle, the 
water, and the solid. The solid body is then placed in the flask 
of water, when it displaces a quantity of water equal to its own 
volume. The displaced water is allowed to run out, the whole 
is again weighed, and loss in weight will indicate the weight 
of the volume of water displaced by the solid. The weight of 
the solid body is then divided by the weight of an equal volume 
of water, so found, and the quotient expresses the specific 
gravity. 

Example : 

Weight of solid body 50 grains. 

Weight of flask of water 200 grains. 

Combined weight 250 grains. 

Weight of flask and solid after water is displaced 
by latter 230 grains. 

Weight of water displaced 20 grains. 

50 -f- 20 =z 2.5, specific gravity of solid. 

Other methods are based upon the Theorem of Archimedes. 

This theory states that a body when weighed in water loses a 

portion of its weight, and the loss represents the weight of an 

equal volume of water. To determine specific gravity by the 

3 



1 8 TEXT-BOOK OF CHEMISTRY 

theorem of Archimedes the solid is first weighed in air, then it 
is suspended by a thread or hair and weighed in water. The 
difference between the two weights represents the weight of a 
volume of water equal to the volume of the solid. The weight 
in air, therefore, divided by the loss of weight in water will give 
the specific gravity. 

If the body to be examined is lighter than water, it is first 
weighed in the air, then attached to a piece of metal heavy 
enough to sink it, and both are weighed. The two are then 
weighed in water, and the loss in weight represents the weight 
of water displaced by both. The piece of metal is then de- 
tached and weighed in air and again in water ; the loss of weight 
indicates the weight of water displaced by the metal alone. 
The difference between the weight of water displaced by the 
two together and that displaced by the metal alone gives the 
weight of water displaced by the light body. The weight of 
the light body is then divided by the weight of water which it 
displaces, and the specific gravity is obtained. 

Example : 

Wax weighs in air 133-7 grains. 

Attached to brass the two weigh 183.7 grains. 

In water the two weigh 38.8 grains. 

Weight of water equal to bulk of brass and wax. 144.9 grains. 



Weight of brass in air 50.0 grains. 

ight of brass in water 44.4 grains. 

Weight of water equal to volume of brass 5.6 grains. 



f We 



Weight of water equal to bulk of brass and wax. 144.9 grains. 

Weight of water equal to bulk of brass alone 5.6 grains. 

Weight of water equal to volume of wax 139.3 grains. 

133.7 -f- 139-3 = 0.9598, specific gravity of wax. 

In case the solid is soluble in water some other liquid of 
known specific gravity is used, and from the weight of this 
liquid displaced, the weight of an equal volume of water is 



DENSITY AND SPECIFIC GRAVITY 1 9 

calculated. The liquids used are alcohol, oil of FlG - 7. 
turpentine or others. For example : The substance /~\ 

is weighed in air, then in oil of turpentine ; the loss 
in weight indicates the weight of an equal bulk of 
oil of turpentine. From this weight of oil of tur- 
pentine of known specific gravity, the weight of 
an equal volume of water is easily calculated, and 
the specific gravity is obtained. 

Example : 

Weight of sugar in air 400 grains. 

Weight of sugar in oil of turpentine 182.5 grains. 

Weight of equal bulk of oil of turpentine.. 217.5 grains. 

Assume the specific gravity of oil of turpentine 

to be 0.87 : then, 

0.87 : 100 : : 217.5 • % — 2 50, weight of equal bulk of water. 
Hence : 

400 -T- 250= 1.6, specific gravity of sugar. 

Hydrometers are instruments used to determine 
the specific gravity of liquids. They usually con- 
sist of a glass tube, the lower extremity of which is 
expanded and weighted so as to hold the instrument 
in a vertical position. The principle upon which 
their action depends is the fact that a solid body 
floating in a liquid heavier than itself displaces a 
volume of liquid equal to its own weight, and for 
this reason the hydrometer will sink deeper in light 
liquids than in heavy ones. By previously testing 
the instrument in liquids of known specific gravity 
and making a corresponding scale on the stem, the 
specific gravity of a liquid in which it may be 
immersed can be easily read off. These instru- 
ments, when made for the purpose of testing spe- 
cial liquids, are called urinometers, alcoholometers, 

lactometers, etc. Hydrometer. 




20 TEXT-BOOK OF CHEMISTRY 

The specific gravity of a gas is determined by finding and 
weighing an equal volume of gas and of the standard, air, 
under the same conditions of temperature and pressure. The 
weight of the gas is then divided by the weight of an equal 
volume of air. 

PHYSICAL CONSTITUTION OF GASES. 

In considering the law of the attraction of masses of matter, 
or gravitation, the question naturally arises, Do gases have 
weight ? The question can be very easily answered by a simple 
experiment. If a glass globe filled with air, and fitted with 
an air-tight stop-cock, be carefully weighed and then the air 
completely exhausted by means of the air-pump, it will be found 
that the vessel is considerably lighter upon re-weighing. This 
loss in weight must represent the weight of the air which the 
globe contained. If the vessel be of sufficient size to contain 
ioo cubic inches the loss in weight will amount to nearly 30 
grains. This weight is made manifest in the enormous force 
with which the air presses down upon the earth's surface, but the 
pressure is so evenly distributed, on account of perfect mobility 
of the particles of air, that it causes no disagreeable effects. Any 
sudden and great change in atmospheric pressure, however, re- 
sults disastrously to the living animal. 

All other gases possess the property of weight. Those that 
are dense will sink to the lower level, but those that are lighter 
than air will rise, being buoyed up by the surrounding medium ; 
just as a light body will rise when set free below the surface 
of water. 

The Barometer. If a glass tube, sealed at one end and 
having a cross section of one square inch, be completely ex- 
hausted of air and inserted into a vessel of mercury, the mer- 
cury will be seen to rise in the tube until it reaches a point 
thirty inches from the surface of the liquid in the vessel. This 



PHYSICAL CONSTITUTION OF GASES 21 

column of mercury is forced up into the empty tube on account 
of the pressure of air on the surface of the liquid. The weight 
of such a column of mercury is found to be about fifteen 
pounds — 14.7 — and the cross section being equal to one square 
inch, the weight of the atmosphere is fifteen pounds to the 
square inch of surface — nearly a ton to the square foot of 144 
square inches. 

The expression, " atmospheres," in pressure, is used to desig- 
nate the amount of pressure to the square inch of surface: 
ten atmospheres, indicating one hundred and fifty pounds to 
the square inch ; two atmospheres, indicating thirty pounds ; one 
atmosphere indicating fifteen pounds, etc. 

The instrument represented in the above experiment, when 
made of proper size and graduated to a scale, is called a 
Barometer, and it is used to measure atmospheric pressure. 
Atmospheric pressure is not constant at any one place, varying 
with climatic changes; it also constantly lessens with increas- 
ing elevation above the sea level. 

Other liquids than mercury may be used to construct a baro- 
meter, but as the height of the column is inversely propor- 
tional to the weight of the liquid used it would be much higher 
with lighter liquids. Water is 13.6 times lighter than mercury, 
and the height of the column would be 13.6 times 30, or about 
34 feet. 

The Air Pump is an instrument for producing a vacuum. 
The vessel in which the vacuum is produced, by exhaustion of 
air, is called the " receiver " of the air pump. This instru- 
ment consists of a hollow cylinder in which a tightly fitting 
piston is moved by its rod. The bottom of the cylinder com- 
municates with the receiver of the pump, and contains a valve 
opening upward; a valve, opening in the same direction, is 
fitted in the piston. When the piston is raised, the lower valve 
opens and air is drawn into the cylinder from the receiver; 



22 



TEXT-BOOK OF CHEMISTRY 



when the piston is depressed, the lower valve closes, the upper 
valve opens, and a cylinderful of air escapes to the surrounding- 
atmosphere. Thus, a cylinderful of air is removed from the 
receiver at each stroke of the pump. 

Sprengel's Air-Pump consists of a vertical glass tube the 
lower end of which dips into a vessel of mercury, the vessel 
being supplied with a spout just above the lower end of the 

Fig. 8. 




Air Pump. 

tube to carry off excess of the liquid. The upper end of this 
tube is attached to a funnel by means of a piece of rubber 
tubing to which is fitted a clamp. From near the upper ex- 
tremity of the vertical tube a lateral tube is extended, to the 
end of which is attached the vessel from which air is to be 
exhausted. To operate the instrument, mercury is poured into 
the funnel and allowed to flow through the vertical tube, the 



PHYSICAL CONSTITUTION OF GASES 



23 




flow being regulated by the clamp. As mercury passes down, 
air is carried with it, until complete exhaustion has occurred 
in the receiver, and the column stands at a height of 30 inches. 

Elasticity, or Tension, is 

, . . Fig. 9. 

a property 01 gases in vir- 
tue of which they constantly 
tend to increase their volume. 
It is due to the fact that the 
molecules of a gas are con- 
stantly in motion, advancing 
in straight lines, and by con- 
tinuously striking against the 
sides of the containing vessel 
produce the phenomenon of 
pressure. The volume, pres- 
sure, and elastic force of gases 
bear relations to each other 
which are expressed in the 
law discovered by Boyle in 
1661, and generally known as 
Boyle's law; it is sometimes 
called Mariotte's law. The 
law may be expressed thus : 
The volume of a gas is in- 
versely as the pressure; the 
density and elastic force are 
directly as the pressure and in- 
versely as the volume. For 
example : If a vessel contains 

100 cubic inches of a gas under a pressure of 10 pounds, the 
volume would be lessened to one-half, one-third, or one-fourth 
of 100 cubic inches if the pressure were increased to 20, 30 or 
40 pounds. The density and elastic force would be increased 




Sprengel's Air Pump. 



24 TEXT-BOOK OF CHEMISTRY 

to the same degree. All vapors, when not near the point of 
condensation, behave like gases in respect to this law. 

HEAT. 

The term, heat, is used to express a definite sensation, and 
also the condition of matter which produces this sensation. 

Two theories have been advanced to explain the phenomena 
of heat. For a long time many philosophers believed heat to 
be a material substance, differing from other matter in lacking 
the property of weight, but existing in combination with other 
bodies, and capable of being transferred from one substance 
to another. The term Caloric was used to designate this 
hypothetical body. 

At present, however, heat is believed to be a form of energy 
and not of matter. This theory was first advanced by Sir 
Humphrey Davy as a result of experiments showing that the 
quantity of heat produced by mechanical energy is directly 
proportional to the amount of energy expended, and not to the 
quantity of matter involved. It is called the Dynamical, or 
Mechanical Theory, and assumes that the phenomena of heat 
are caused by a vibratory or oscillatory motion of molecules and 
atoms. The vibratory motion is capable of being transferred 
from one substance to another, and the degree of heat bears 
a direct relation to the rapidity of vibrations. 

PHYSICAL EFFECTS OF HEAT UPON MATTER. 

Expansion. 

One of the first and most visible effects of heat upon matter 
is a gradual increase in the volume of a heated body. Ex- 
pansion as a result of heat occurs in solids, in liquids and in 
gases. 

Expansion of Solids. If an iron bar be made to fit accu- 
rately to a gauge when cold, it will be found to have expanded 






HEAT • 2 5 

in all its dimensions when heated; and when allowed to cool 
down again, it will once more fit the gauge. 

The degree of expansion for the same increment of heat is 
not alike for every solid substance, and the rate of expansion 
increases with increase of temperature. The force exerted in 
the expansion of solid bodies by heat is so great as to necessi- 
tate an allowance for change in volume of the component parts 
of structures of iron, or other metal, attendant upon changes 
of temperature. 

Expansion of Liquids. The property of expansion by heat 
in liquids occurs to a greater extent than in solids, as may be 
shown by placing a liquid in a glass flask having a long narrow 
neck, and heating. Under these conditions, the level of the 
liquid in the neck of the flask will be seen to rise, indicating 
increase in .volume on the part of the former, and showing, 
furthermore, that the rate of expansion of the contained liquid 
is greater than that of the container. With increase of heat 
the rate of expansion also increases, as in the case of solids. 
Mercury expands very regularly from o° to ioo° C. ; and, for 
some distance above that point of temperature, expansion on 
the part of the glass container about equalizes the increased rate 
of expansion of the metal. Mercury expands about 1/64 of 
its volume from o° to ioo° C. 

Water gives a very remarkable deviation from the law of 
expansion by heat, within certain limits of temperature. 
Throughout ordinary temperatures it behaves like other bodies. 
When cooled, it slowly contracts in volume until the tempera- 
ture reaches 4 C. (39.2 F.), but below this point expansion 
begins, and continues as the temperature sinks, until the freez- 
ing point is reached at o° C. In freezing, there is a sudden and 
great increase in volume. This unusual behavior on the part 
of water causes its coldest portions to rise to the surface, on 
account of their decrease in specific gravity, whenever the tern- 



26 TEXT-BOOK OF CHEMISTRY 

perature draws near the freezing point. These conditions are 
sufficient to account for the formation of ice upon the surface 
of bodies of water. The expansion of congelation at the 
moment of freezing is a phenomenon observed in many other 
bodies when they pass from the liquid to the solid state, and is 
of a different nature from that observed before the freezing 
point is reached. The force of the expansion of congelation 
is very great, and is sufficient to burst cast iron shells in which 
water has been placed and exposed to low temperatures. This 
force can be opposed by physical means, however, and to such 
an extent that the temperature of water can be carried far 
below the freezing point without congelation taking place. The 
expansion of congelation serves a very important function in 
nature. Water, accumulating in the crevices of rocks and 
soils, upon freezing, causes disintegration and exposure of 
soluble constituents, which are washed out by falling rains, 
and contribute to the sustenance of growing plants. 

From what has been said in the above, it can be seen that 
the temperature of greatest density of water is that point at 
which contraction in volume with reduction of temperature 
ceases. This point of temperature is 4 C, or 39.2 ° F. \ 

The Thermometer. The sensations are inaccurate when 
used for the purpose of measuring the degree of heat : a sub- 
stance feels hot, or cold, in accord with a higher, or lower, 
temperature than that of the body. The instrument used for 
determining temperature is called a thermometer, and advan- 
tage is taken of the expansibility of matter by heat in selecting 
the material from which it is made. In constructing a ther- 
mometer, a glass tube is selected, having a capillary bore of 
uniform size and a bulb blown at one end. The bulb is heated 
to expel air, and the open end of the tube is dipped into a 
vessel of mercury. As a result of this, mercury rushes in the 
bulb by pressure of the atmosphere, partly filling the instru- 



HEAT 



2/ 



Fig. 10. 



ment. If the bulb of the thermometer be now heated, so as 
to volatilize a portion of its contents, it may be completely filled 
by dipping the open end of the tube in the vessel of mercury. 
The instrument is now heated until 
sufficient mercury is expelled to allow 
the remainder to stand at a con- 
venient height, and it is again heated 
until the contents completely fill the 
tube, when the latter is quickly sealed. 
When the mercury recedes a vacuum 
is left in the upper part of the in- 
strument. 

The thermometer has now to be 
graduated by means of a scale, to 
which it is attached, or which is 
marked on the stem. This is done 
by placing it in melting ice for one 
of the fixed points of temperature, 
and then in steam rising from boil- 
ing water for the other. In the 
Centigrade scale, the freezing point 
is marked o°, and the boiling point 
ioo° ; the intervening space being 
divided into 100 equal subdivisions. 
In the Fahrenheit scale, the freezing 
point is marked 32 °, and the boiling 
point 212 ; the intervening space 
being divided into 180 equal parts. 
In the Reaumur scale, the freezing 
and boiling points are marked 0° 

and 8o°, respectively, with 80 equal divisions of the scale be- 
tween these two points. 

The divisions of the scale are also extended below the zero 
mark, and the readings here are indicated by the minus sign 




Thermometers, Showing the 
Three Different Scales. 



28 TEXT-BOOK OF CHEMISTRY 

( — ). Readings above zero are expressed by using the plus 
sign ( + ). 

The relation between the reading of the three scales is ex- 
pressed by the figures which show the number of divisions 
between the freezing and boiling point for each scale : 80 for 
the Reaumur, 100 for the Centigrade, and 180 for the Fahren- 
heit. These numbers when reduced to their simplest terms are 
4, 5, and 9, and they are used in converting the readings of one 
scale into those of the other. The Fahrenheit scale having been 
given 32 at zero, this number must be deducted when Fahren- 
heit degrees are calculated to the degrees of the other scales, 
and added, when Reaumur or Centigrade degrees are calcu- 
lated to Fahrenheit. 

To convert C. degrees to F. degrees ; multiply by 9, divide the 
product by 5, and add 32. 

Example : Convert 4 degrees C. to F. degrees : 

5 : 9 : : 4 : x = 7.2 + 32 = 39.2 F. 

Example : Convert — 10 degrees C. to F. degrees : 

5 : 9 : : — 10 : x — — 18 + 32 = + 14 F. 

To convert F. degrees to C. degrees; subtract 32, multiply 
by 5, and divide the product by 9. 

Example : Convert 60 degrees F. to C. degrees : 

60 — 32 = 28. 

9: 5:: 28:^= 15.5 C. 

Example : Convert — 20 degrees F. to C. degrees : 

— 20 — 32 = — 52. 

9:5:: — 52 : x = — 28.8 C. 

The spirit thermometer is intended for measuring unusually 
low temperatures, and is made by using colored alcohol in- 
stead of mercury for filling the bulb. 



HEAT 29 

Expansion of Gases. When solids and liquids are heated 
the amount of expansion varies with different substances, but 
in the case of gases we find great uniformity in expansion. The 
amount of expansion for a given quantity of heat is alike for 
all gases, and this statement applies equally to vapors when the 
temperature is remote from the point at which they condense. 
The Law of Charles refers to the regularity with which gases 
expand under the influence of heat, and may be expressed 
thus : " With constant pressure, the volume of a gas increases 
regularly with increase of temperature, and decreases regularly 
with decrease of temperature." If the gas be confined and ex- 
pansion prevented, the pressure will increase in proportion to 
the increase of temperature. The amount of expansion or con- 
traction of a -gas is 1/273, or .3665 per cent, of the volume at 
o° C. for each degree of the same scale; and, therefore, 100 
cubic inches of a gas at o° C. would become 136.65 cubic 
inches at the temperature of ioo° C. 

Absolute Zero. If a gas contract 1/273 of its volume at 
zero for each degree of the same scale when cooled, it is clear, 
from a mathematical standpoint, that at 273 ° below zero it 
would be resolved to nothing. While this low temperature 
has never been reached in actual experiment, it is known that 
the gas would become a liquid, and then a solid, long before 
its temperature fell to this point. The point of temperature at 
which a gas shall have contracted in volume until it, theoreti- 
cally, cease to exist, is called absolute zero; and here it is be- 
lieved that all molecular motion is suspended, and that matter 
is devoid of heat. Absolute zero for the Centigrade ther- 
mometer is 273 ° below o° ; for the Fahrenheit it is 459 below. 
The absolute temperature of a substance may be found by 
adding 273 in the Centigrade, or 459 in the Fahrenheit scale, 
to the given temperature. 

Calculations for Correction of Volume. Since gas volume 



30 TEXT-BOOK OF CHEMISTRY 

varies with varying conditions, it is always necessary to state 
the temperature and pressure at which observations are taken 
in speaking of gases. In statements of the density of gases, 
normal temperature and pressure are assumed, which is 760 
m.m. of mercury in pressure, and 0° C. (32 F.). It fre- 
quently becomes necessary, therefore, to calculate the volume 
of a gas from a given temperature to the normal. Since the 
volume of a gas is directly proportional to the absolute tem- 
perature, the correction is easily made, as shown in the fol- 
lowing example : 

If a gas measure 50 c.c. at 40 C, its volume at o° C. is 
found by the proportion : 

50 c.c. : (40 +273°) ::^:(o° + 273°), 
50 : 313 : : x : 273, 

50 X 273 _ 6l + volume at o° C. 

313 

In the above calculation, the pressure is assumed to remain 
constant. Suppose the 50 c.c. of gas at 40 C. to be under a 
pressure of 730 m.m. ; then, as shown above, its volume becomes 
43.61 c.c. at o° C. and 730 m.m. What the volume would be- 
come at 760 m.m. can be found by reference to Boyle's law, 
which says : " The volume of a gas is inversely proportional to 
the pressure." Therefore : 

760 : 730 : : 43.61 : x, 
730 X 43-6i 



760 



= 41.88 c.c. at o° C, 760 m.m. 



TRANSMISSION OF HEAT. 

If two bodies, having different degrees of temperature, be 
brought in contact, the rapidly vibrating molecules of the hot 
body will transfer a part of their motion to the slowly-moving 
molecules of the colder substance, until finally, a point is 
reached when the velocity of their molecular vibration is the 



HEAT 3 1 

same. The two have then reached a state known as the mobile 
equilibrium of temperature, in which they exchange equal 
amounts of heat. This mutual exchange of heat not only takes 
place between bodies in contact, but occurs in several other 
ways: 

i. Conduction. If one end of an iron bar be held in the 
flame of the Bunsen burner, the other extremity soon becomes 
too hot to be borne by the hand of the operator. Conduction 
is this property of transmitting heat through the mass of a body, 
from one molecule to the next, and it is developed to different 
degrees in different substances. Metals are the best conductors 
of heat ; gases and liquids, except mercury, are poor conductors. 
The relative heat-conducting power of different bodies is shown 
in the following table; taking silver as the standard of com- 
parison : 

Silver 1.000 Water 0.002 

Copper 0.960 Glass 0.0005 

Gold 0.530 Wool 0.00012 

Iron 0.200 Paper 0.000095 

Stone 0.006 Air 0.000049 

2. Convection means carrying, or transferring heat by 
means of the movement of masses of molecules, and generally 
takes place in the movement of heated currents of gases or 
liquids. If a long narrow test-tube be nearly filled with water, 
the liquid may be boiled in the upper part of the tube while it 
remains cool in the lower end; thus showing the low con- 
ductivity of water. But suppose this tube be heated at its 
lower extremity ; in that case, the heated portions of the liquid, 
lessening in specific gravity by expansion, rapidly rise to the 
surface, and, at the same time the colder portions fall to the 
bottom of the tube, forming rapidly circulating currents by 
means of which heat is evenly distributed throughout the liquid. 
Heat distribution, in this manner, is known as convection. 



32 TEXT-BOOK OF CHEMISTRY 

3. Radiation is the transmission of heat through space. A 
heated body suspended in air, or in a vacuum, will give out 
heat to surrounding objects. In order to explain this trans- 
mission of heat through space, as well as the phenomena of 
light and electricity, it is assumed that an exceedingly tenuous 
and elastic medium pervades all space and exists between the 
molecules of matter; this hypothetical substance is called ether. 
The molecular vibrations in a heated body produce correspond- 
ing oscillations, or waves, in the surrounding ether, whereby 
heat is radiated in straight lines in all directions from the hot 
body. 

The Thermal Unit. The temperature of a substance ex- 
presses the degree, or intensity of heat ; the quantity, or amount 
of heat of a body is expressed in heat units, or calories. A 
very fine platinum wire, when heated to the high temperature 
of redness, may yet be held between the fingers without injury 
because the quantity of heat is so small. The thermal, or heat 
unit is the quantity of heat required to raise the temperature 
of one pound of water from 32 ° to 33 ° F. The calorie is the 
quantity of heat required to raise the temperature of one gram 
of water from o° to i° C. ; but, since 1 gram of water has 
proved to be too small a standard for accurate observations, 
the great calorie is generally employed, and this is the quan- 
tity of heat required to raise the temperature of 1 kilogram of 
water from o° to i° C. 

SPECIFIC HEAT. 

Equal weights of different substances having the same tem- 
perature require different quantities of heat to raise their tem- 
perature through the same number of degrees. Specific heat 
is an expression showing the quantity of heat required to raise 
the temperature of a given weight of a substance through a cer- 
tain number of degrees, compared with the quantity of heat 



HEAT 33 

required to raise the temperature of the same weight of water 
through the same number of degrees. The standard of com- 
parison in expressions of specific heat is the thermal unit. The 
quantity of heat which will raise the temperature of a pound of 
water from 32 ° to 33 ° will raise the temperature of two pounds 
of olive oil from 32 ° to 33 °. Hence we say the specific heat 
of olive oil is one-half — its resisting power to the influence of 
heat is one-half that of water. One pound of water at ioo° 
mixed with one pound of water at 40 , will give two pounds 
of water having a mean temperature of 70 . One pound of 
water at ioo° and one pound of olive oil at 40 , will give two 
pounds of the mixture having a temperature of 8o°. The 
twenty degrees of heat lost by the pound of water, when mixed 
with the pound of olive oil, were sufficient to raise the tem- 
perature of the oil forty degrees ; i. e., from forty to eighty de- 
grees. Therefore, the specific heat of oil is said to be 20/40, or 
one-half that of water. One pound of water at ioo° and one 
pound of mercury at 40 give two pounds of mixture at 98 ; 
according to which, the specific heat of mercury would be 2/58, 
or 1/29. The specific heat of a body increases as its tem- 
perature rises. 

LATENT HEAT. 

Liquefaction. Many solid bodies, when heated, not only ex- 
pand, but when the degree of heat is sufficiently intense they 
become liquids. Some of these become soft and pasty just 
before fusing, as iron, glass, etc., while others pass directly from 
the solid to the liquid state, as lead and zinc. Most bodies when 
in the act of melting expand, but water is an exception to this 
rule. During melting, eleven volumes of ice form about ten 
volumes of water. 

During the passage of a body from the solid to the liquid state 
the temperature remains constant until transition is complete, 
no matter how great the supply of heat may be. It is therefore 



34 TEXT-BOOK OF CHEMISTRY 

concluded that a certain amount of heat is absorbed by the body 
in changing its state of aggregation. This heat is not indicated 
by the thermometer, and is called latent heat. If a pound of 
water at o° be mixed with a pound of water at 8o°, a mean 
temperature of 40 is obtained. But if a pound of powdered 
ice at a temperature of o° be mixed with a pound of water at 
8o°, the temperature of the two is brought to o° ; the ice, how- 
ever, will have melted. It is thus seen that the heat required 
to convert a pound of ice at o° to a pound of water at o° would 
be sufficient to raise the temperature of a pound of water from 
o° to 8o°. 

The production of artificial cold by freezing mixtures de- 
pends upon these physical phenomena. Whenever rapid lique- 
faction can be brought about, unattended by chemical change, 
great cold is produced. A mixture of a pound of powdered 
ice and salt gives a temperature of — ^7-7° '• Powdered crys- 
tallized calcium chloride and snow, reduce the temperature 
enough to freeze mercury. Rapid solution of solids in liquids 
also causes great reduction of temperature. 

Volatilization. If a liquid be subjected to a constant source 
of heat, its temperature will gradually rise until the boiling point 
is reached, and will there remain constant in spite of continued 
heating. It will be noticed, however, that the liquid is being 
volatilized, and it is in the conversion of liquid into vapor that 
the heat is consumed. Whenever matter passes from the liquid 
to the gaseous state, a quantity of heat is absorbed, or made 
latent, and apparently disappears. The quantity of heat lost 
in the conversion of a liquid into a gas is much greater than that 
which disappears when a solid is converted into a liquid. One 
part of steam at a temperature of ioo° C, in becoming water 
at ioo° C, parts with enough heat to raise the temperature of 
5.4 parts of water from o° to ioo° C, or a sufficient quantity 
of heat to raise the temperature of 540 parts of water i°, if it 



HEAT 3 5 

were possible to prevent the loss of any of the liberated heat. 
Whenever matter passes from the gaseous to the liquid, or from 
the liquid to the solid state, heat is disengaged to the same 
extent that it is absorbed when the opposite change occurs. 

By placing water in a vessel whose sides are perfectly clean 
and smooth, in a room in which the air is free from particles 
of dust, the temperature may be greatly reduced below the 
freezing point, and the water remain liquid. If now, a grain 
of sand or small particle of other solid be dropped in, so as to 
form a nucleus for crystallization, ice suddenly forms and the 
temperature rises to o°. A supersaturated solution of sodium 
sulphate can be made by making a hot saturated solution and 
placing it in a tightly corked bottle. When the solution cools 
down, it remains liquid, but when the cork is removed, or a 
crystal is dropped in, rapid crystallization of the salt takes 
place, accompanied by an appreciable rise in temperature. 

Boiling. Many liquids when heated to a sufficiently high 
temperature are converted into vapor. When the bubbles of 
vapor forming within them acquire a sufficient degree of tension 
to overcome the cohesion of the liquid, adhesion to the vessel, 
and pressure upon the surface, a condition of ebullition or boil- 
ing is established. Each liquid has its own boiling point under 
certain given conditions, and it will be seen that these condi- 
tions are cohesion, adhesion and pressure upon the surface : by 
varying these, the boiling point may also be varied. The boil- 
ing point of water under ordinary atmospheric pressure is ioo° 
C, or 212° F. 

The solution of less volatile substances in a liquid raises the 
boiling point. W T ater, when saturated with common salt, boils 
at the temperature of 109 C. ; when saturated with potassium 
carbonate it boils at 135 C. ; and, when saturated with calcium 
chloride, boiling takes place at 179 C. 

The boiling point is also influenced by the character of the 



$6 TEXT-BOOK OF CHEMISTRY 

containing vessel. In a vessel having a rough metallic surface, 
water boils at 100 C. or slightly below this point; but if the 
surface be smooth and polished, as in a glass flask, the tem- 
perature often rises a few degrees above ioo° C, when violent 
or explosive boiling takes place for a moment, the temperature 
then sinking to ioo° C. This explosive boiling, caused by adhe- 
sion between the sides of the vessel and the heated liquid, can 
be prevented by dropping in a few angular fragments of in- 
soluble solid, so as to give points from which the forming 
vapor may escape. 

Pressure is an important factor in influencing the boiling 
point. When the pressure is small, as on high mountains or 
in a vacuum, water boils at a low temperature; but when it 
is increased by confining the steam, the boiling point is raised 
with increasing pressure. Temperature of water in a boiler 
at the pressure of 150 pounds to the square inch (ten atmos- 
pheres) is about 360 F. It is thus seen that pressure upon the 
surface of a heated liquid has a restraining influence to prevent 
its conversion into vapor. It has been found by experiment, 
however, that there is a point of temperature for each volatile 
liquid at which it becomes a vapor, regardless of the amount of 
pressure to which it may be subjected, and this point is re- 
ferred to as the " critical temperature " of the substance. 

The vapors of liquids behave in all respects like other gaseous 
bodies as long as they are not in contact with the liquids from 
which they are formed, and as long as the temperature is dis- 
tant from the point of condensation. The condition of maxi- 
mum density of a gas or vapor is that point beyond which its 
density cannot be increased without the gas assuming the liquid 
state. The increase in density of a gas is effected by two agen- 
cies, viz., pressure and cold; and when these are combined, a 
powerful influence is brought for the liquefaction of a gas. On 
account of the perfect resemblance of vapors to gases, it was 



HEAT 



37 



supposed that the latter could be liquefied by means of pressure 
and cold, and it has been found that all of the gases which were 
thought to be permanent, can be liquefied by this means. 



Fig. ii. 




Distilling Apparatus. (After Rockwood.) 



Distillation. The process of distillation has for its object 
the separation of liquids rising in vapor at different tempera- 
tures, or the removal of a volatile liquid from a substance in- 
capable of being volatilized. The same process, when applied 
to those bodies which pass directly from the solid to the vapor- 
ous condition, and back again, is called sublimation. 

Every distilling apparatus consists essentially of a boiler, or 
retort, in which the substance is vaporized ; and a condenser, 
in which the vapor is cooled, and returns to its original condi- 



38 TEXT-BOOK OF CHEMISTRY 

tion. These are made in many different forms, to suit the pur- 
poses for which they are intended. 

Fractional distillation is the separation of liquids having dif- 
ferent boiling points from a mixture of liquids, by repeatedly 
distilling, and collecting the vapors that come over at different 
temperatures. 

Destructive distillation is the process of heating non- volatile 
organic bodies in a closed retort, so as to exclude oxygen, and 
collecting the volatile products which form. 

LIGHT. 

Light is the agent which, by its action on the retina, excites 
the sensation of vision. Two theories have been advanced to 
explain the cause of the phenomena of light. One, which was 
proposed and advocated by Sir Isaac Newton, is that luminous 
bodies emit infinitely small particles from every point of their 
surface, and that these, by penetrating the eye and falling upon 
the retina, produce the sensation of light. This theory has been 
abandoned, and at the present time light is believed to be caused 
by the vibrations of ether, or by ether waves. 

Ether waves produce different results depending upon the fre- 
quency and amplitude of the vibrations ; comparatively slow 
vibrations cause the transmission of heat, more rapid vibrations 
produce light, and vibrations of still greater frequency excite 
chemical action. 

The heat waves have a rate of vibration less than 477,000,- 
000 millions per second, and they are sometimes called infra- 
red rays. The vibrations in light waves extend from 477,000,- 
000 millions to 699,000,000 millions per second; the slowest 
vibrations, which are the longest waves, producing red light, 
and then, with increasing frequency of vibration, the following 
colors are formed in succession : orange, yellow, green, blue, 
indigo and violet. 






LIGHT ' 39 

The range of wave-lengths for light of different colors is 
not great. Experiments indicate that the length of ether waves 
for red light is .0000271 of an inch, and for violet light, 
.0000155 of an inch. 

Ether vibrations of greater frequency and smaller amplitude 
than occurs in the violet light, constitute a form of energy which 
is beyond the range of the field of vision ; these are referred to 
as the ultra-violet, or actinic rays, and are capable of exciting 
chemical action. 

All of the ether waves are probably the same in their essen- 
tial nature,- but differ only in degree; it is therefore frequently 
the case that they are all set in motion from one body at the 
same time. The sun's rays contain all these forms of energy, 
and are thus capable of producing heat, light and chemical 
action. 

Color is produced by the reflection of certain constituents of 
white light, which go to make up the tint, while the rest is ab- 
sorbed. White is produced by those bodies which reflect all 
of the light they receive, while black objects absorb all that 
falls upon them. All bodies are black when there is no light. 

Light of itself is invisible, as may be shown by allowing a 
ray to pass through a dark room : if the air be free from float- 
ing particles it cannot be seen, but any substance placed in its 
track will become visible, or if it fall upon the eye its source 
will become apparent. Light, therefore, is the medium by 
which we see other bodies, but itself cannot be seen. The atmos- 
phere serves a very important function in the diffusion of light, 
thus throwing it in all directions, and causing bodies to be vis- 
ible which are not in the direct path of luminous rays. If one 
could stand in space, where there is no atmosphere to give light 
diffusion, he would be surrounded by the blackness of night, 
except when his eyes were turned upon the glaring orb of the 
self-luminous sun, or to the shining point of reflected light from 
some planet. 



40 



TEXT-BOOK OF CHEMISTRY 



Fig. 12. 



Light passes in a straight line in all directions from a lumi- 
nous point as long as the medium it is traversing remains of 
the same density; its velocity is 186,000 miles per second. A 
change in the density of the medium through which the light 
is passing, is accompanied by a change in direction and a slight 
change in velocity. 

Transparent bodies are those which allow the free passage 
of light ; opacity is the property of preventing its passage ; and 
a translucent substance allows only a small amount to pass 
through. 

Reflection. When a ray of light falls upon a mirror or 
polished surface which it cannot penetrate, it is reflected into the 
medium from which it came. If a line be drawn perpendicular 

to the reflecting surface, it 

will be found that this line 

forms an angle with the 

incident ray, which is equal 

to the angle it forms with 

the reflected ray; therefore, 

we say that the angle of 

incidence is equal to the 

angle of reflection. 

The light reflected from visible bodies is diffused, or thrown 

in all directions, coming from many minute surfaces of which 

the exterior of the body is composed. 

Refraction. A medium is a space or substance through 
which light is capable of passing. As long as the medium re- 
mains of the same chemical composition and density, the light 
travels in a straight line; but if a ray of light be passed from 
one medium to another of greater density, the direction of the 
ray is changed and the change of direction is found to be 
towards a line perpendicular to the surface of the medium. On 
emerging and passing into a rare medium, the reverse is found 




Showing Direction of a Ray of Light 
in Reflection. 



LIGHT 



41 




Showing Direction of a Ray of Light 
in Refraction. 



to be the case, and the light is bent away from the same per- 
pendicular line. This change of direction by bending is called 
refraction. The amount of refraction, or bending, increases 
with increasing obliquity 

of the incident ray. The IG * I3 ' 

perpendicular ray is not 
refracted. 

The angle formed by 
the incident ray with a 
perpendicular, bears a con- 
stant ratio to the angle 
formed by the refracted 
ray, in each refracting 
substance; this ratio ex- 
presses the index of re- 

, fraction for that substance. While the amount of refraction 
increases with increasing obliquity of the incident ray, with a 

given body, yet the rela- 
tion between the sizes of 
the angles of incidence 
and refraction remain the 
same. The index of re- 
fraction expresses the re- 
lation between the sine of 
the angle of the incident 
ray (a) and the sine of the 
angle of the refracted ray 
(b), and is a fixed quan- 
tity for each substance. 
Dispersion. If a ray of light is passed through a refracting 
medium whose sides are not parallel, the direction in which it 
travels is completely changed. When light is passed through 
a prism its direction is changed on this account, and upon 




Showing Index of Refraction. 



42 



TEXT-BOOK OF CHEMISTRY 



emerging, it is dispersed, or broken up, into the colors of the 
rainbow. When the base of the prism is turned up, and the 
emergent rays are thrown upon a screen, the colors presented 
from above downward are, violet, indigo, blue, green, yellow, 
orange and red. This dispersion of white light is due to dif- 

Fig. 15. 




Spectroscope. (After Traube.) 



ferences in the degree of refrangibility of its component parts ; 
the violet being most refrangible, and red the least. The image 
formed in this way is called a spectrum. 

The Spectroscope is an instrument used for observing the 
spectrum. Differently constructed instruments are used, but the 
one most frequently employed consists of three telescopes 
directed upon a prism, mounted on a stand. One of the tele- 
scopes receives the light through a narrow slit in its distal 
extremity, while near the other end a convex lens is fixed, called 
" the collimeter," which throws the light in parallel beams upon 
the prism. A second telescope, through which the spectrum 



LIGHT - 43 

is observed, receives the dispersed light, and is adjusted to the 
observer's eye. The third tube contains a mounted scale. This 
scale when illuminated, casts its image on the face of the prism, 
and is seen by the observer just above or below the spectrum. 

When light from a luminous flame is observed through the 
spectroscope it is found to be broken up into its constituent 
colors and the image is called a continuous spectrum. 

Bright Line Spectra. If we place a salt of sodium upon a 
piece of platinum wire, and hold this in the non-luminous flame 
of the Bunsen burner, before the spectroscope, a bright yellow 
line will be observed in the spectrum, occupying the position 
held by yellow in the continuous spectrum. It will be observed 
at the same time that all the other parts of the spectrum remain 
dark ; only the bright yellow line of sodium appearing. If we 
examine the spectra given by other elements, each one will 
show its own characteristic bright lines, no two appearing alike. 
By making use of this fact, the spectroscope can be used as an 
instrument of analysis. In examining metallic salts, the metals 
are so much more luminous than the non-metals, that only the 
spectra of the former are seen. 

Absorption Spectra. Suppose we vary the above experi- 
ment by placing before the spectroscope a luminous flame, and 
then volatilize a compound of sodium, by heating it between the 
source of light and the instrument. The spectrum, when ob- 
served, will be continuous, except that a dark line appears in 
the exact position formerly occupied by the bright yellow line. 
We find, therefore, that while incandescent sodium vapor gives 
only a bright line in the spectrum; if white light be passed 
through sodium vapor, this bright line becomes a dark line in 
the continuous spectrum. We conclude, from these observa- 
tions, that the kind of light waves which sodium vapor gives 
out when heated, will also be absorbed from white light by the 
vaporous metal. 



44 TEXT-BOOK OF CHEMISTRY 

Other elements, examined under similar conditions, present 
their own characteristic dark lines. Such spectra as these are 
called absorption, or reversed spectra. 

White light from the sun, when examined by the spectro- 
scope, shows a number of dark lines which correspond to simi- 
lar appearances from such elements as iron, sodium and hydro- 
gen. These lines are named for their discoverer, and are called 
Frauenhofer lines. These appearances in the solar spectrum 
lead to the conclusion that the sun consists of an incandescent 
central mass, surrounded by elements in the condition of vapor. 

Certain parts of white light are absorbed by many substances 
in solution; and this action is sufficiently characteristic to per- 
mit identification of the substance. Upon this fact depends the 
use of the spectroscope in medicine and toxicology for the 
recognition of blood and solutions of organic or mineral com- 
pounds. 

Fluorescence is a phenomenon which occurs as a result of 
change in the degree of refrangibility of light. If a solution 
of quinine be examined by reflected light, a pale violet color 
will be noticed ; this is due to the power of the solution to lessen 
the degree of refrangibility of ultra-violet rays, thus bringing 
them in the field of vision. Other bodies than quinine possess 
this power, and some substances will change the refrangibility 
of light already in the field of vision. A change in degree of 
refrangibility is accompanied by a change in color. 

Polarization. Certain transparent crystals possess the re- 
markable property of causing a single incident ray of light, in 
passing through them, to be split into two. A crystal of Ice- 
land spar (crystallized calcium carbonate) shows this prop- 
erty to a very high degree and, if it be placed over a printed 
page, the characters underneath all appear double. 

If the crystal of Iceland spar be placed over a black spot on 
a piece of paper, two spots will be seen, and if the paper be 



LIGHT 



45 



gradually turned, one spot appears to remain stationary, while 
the second is observed to rotate around the first. The ray of 
light representing the stationary spot is called an ordinary ray; 
that from the movable spot, an extraordinary ray. 



Fig. i 6. 




Polarization by Refraction. 



Fig. 17. 



The extraordinary ray possesses unusual properties in that it 
does not follow the laws of reflection, refraction or transmis- 
sion which govern ordinary light. A ray of light having these 
unusual properties is said to be polarized. The production of 
this change in the char- 
acter of light by passing 
it through a transparent 
substance is polarization 
by refraction. 

Furthermore, light may — 
be polarized by reflection, — 
as may be seen by allow- 
ing it to fall upon the sur- 
face of plate glass at an 
angle of 54 degrees and 
45 minutes. Polarization by reflection occurs whenever the 
line formed by the reflected ray makes a right-angle to the 
direction of the refracted ray. 




5 



^fieFBACTFO ffAY 



Polarization by Reflection. 



4 6 



TEXT-BOOK OF CHEMISTRY 



There is one direction (sometimes two) in every doubly re- 
fracting crystal, in which light may be passed without being 
changed; so that an object looked at through the crystal in 
this direction does not appear double. A line traversing this 
path through the crystal is called the optical axis. 

Some crystals which doubly refract light will absorb the 
ordinary ray and allow the extraordinary, or polarized, ray to 
pass through. The mineral tourmaline is a body possessing 
this property. Two plates of tourmaline, cut parallel to the 



Fig. i! 



\y 





Action of Tourmaline Crystals Upon Polarized Light. 



axis of the crystal, can be used to examine some of the proper- 
ties of polarized light. If light be passed through one of these 
crystals, it is polarized ; if now we place the other crystal behind 
the first, in a position in which their axes are parallel, the light 
passes without obstruction. But suppose we place the second 
crystal in such manner that the axes of the two are at right 
angles; the result will be complete obstruction to the passage 
of light. The first of these crystals, used to polarize the ray, 
is termed the polarizer, while the second, used to examine the 
ray, is called the analyzer. 

In ordinary light, it is assumed that ether vibrations take 
place in every plane at right angles to the direction of the ray ; 
but in polarized light, it appears that the vibrations are limited 
to one plane. This belief is based upon the peculiar action just 
observed with the tourmaline crystals. A piece of tightly 



LIGHT 



47 



drawn cord will vibrate through two oblong apertures in sheets 
of cardboard, as long as the openings are parallel, but if they be 
placed at right angles, vibration ceases. This is analogous to 
the vibrations of polarized light through tourmaline plates. 

Fig. 19. 



nji 



JrvnAA j. 



Ofb 



V 



Diagram Showing Action of Tourmaline Plates. 

Circular Polarization. If two polarizing crystals be placed 
at right angles to each other, so that light passing through the 

Fig. 20. 




Diagram Showing Action of Tourmaline Plates. 

first is completely obstructed by the second, and then a piece 
of rock crystal interposed between; the light will be turned, 
or rotated, in such manner as to pass through the crystals. 



4 8 



TEXT-BOOK OF CHEMISTRY 



This action of the rock crystal is known as circular polariza- 
tion, and it is exerted by many substances. Those which ro- 
tate to the right are called dextro-rotatory; those which rotate 
to the left are called levo-rotatory : both classes of bodies are 
said to be optically active. 

The Polariscope, or Polarimeter, is an instrument which 
is used for examining polarized light. It consists essentially of 

two Nicol's prisms, such as 
have just been described. 
One of the prisms acts as 
a polarizer, and receives 
the light; the other is the 
analyzer, and can be turned 
through the degrees of a 
circle upon a disk. The 
substance to be examined 
is dissolved in a suitable 
liquid and placed in a glass 
tube. The tube, having 
been closed at both ends 
by transparent glass plates, 
is inserted in a horizontal 
position between the two 
Nicol's prisms upon the 
stand of the polariscope. 
The Nicol's prisms, having 
previously been placed so as to obstruct the light, will now per- 
mit its passage if the substance be optically active. The analy- 
zer is then turned until light is again cut off, and the number 
of degrees of a circle required to effect this result indicates the 
amount of circular polarization of which the substance is 
capable. 

Since the amount of rotation of the ray of polarized light 




Polariscope. 



LIGHT 49 

varies with strength of solution and length of tube, as well as 
character of substance, a standard has to be adopted with re- 
gard to these factors. 1 The specific rotatory power of a sub- 
stance may be defined, as that amount of angular rotation, 
expressed in degrees of a circle, produced by one gramme of 
substance per c.c. of volume, in a tube one decimeter in length. 

Heating and Chemical Action of Different Parts of the 
Solar Spectrum. Reference has already been made to the 
action of' ether waves beyond the range of the field of vision. 
If we now examine the different colored lights in the spectrum, 
by means of a delicate thermometer, it will be observed that the 
temperature slightly increases from the violet to the red end of 
the image; and when certain kinds of glass are used for the 
prism, the highest temperature is found to be beyond the visible 
red rays. The character of a substance from which the prism 
is made will determine to some extent the temperature of dif- 
ferent parts of the spectrum, since many transparent bodies 
have the power to absorb heat. Transparent crystals of rock- 
salt do not possess the power to absorb heat, and the spectrum 
from a piece of this substance shows the highest temperature 
far beyond the red rays. It is thus seen that the portion of 
light which has the highest heating capacity is that which pos- 
sesses the lowest degree of refrangibility. 

The power of light to excite chemical action is a matter of 
common observation. Chlorine and hydrogen combine under 
the direct influence of sunlight; and salts of iodine, silver and 
many other elements are decomposed by its action. It is not 
always the luminous ray, however, which excites this action. 
That portion of the spectrum beyond the violet and out of the 
field of vision possesses this property in the highest degree, and 

1 Amount of rotation varies also with character of light, temperature, 
and character of solvent. Monochromatic light, having one wave- 
length and one degree of refrangibility, must be used. 
5 



50 TEXT-BOOK OF CHEMISTRY 

the radiant energy causing this action is called the actinic, or 
chemical rays. Though the power to excite chemical action 
is not confined to any one part of the spectrum, yet it is more 
strongly developed towards and beyond the violet end. We 
thus see that the chemical rays possess the highest degree of 
refrangibility. 

ELECTRICAL ENERGY. 

MAGNETISM. 

Certain kinds of iron ore known as magnetic iron ore, or load- 
stone, are found to possess the unusual property of attracting 
small pieces of iron, and of causing them to adhere. Bodies 
of this character are called natural magnets ; and their power to 
attract is found to be most strongly developed at the extremi- 
ties, which are called poles, while at the middle this power is 
almost entirely absent. The middle of the magnet constitutes 
the neutral zone. 

If a piece of this loadstone be rubbed in a certain manner over 
a bar of steel, its properties will be communicated, and the 
steel will also become a magnet. Soft iron is capable of being 
magnetized, but its magnetism is of a temporary character, and 
disappears as soon as the magnetizing agent is withdrawn. 
The force of magnetism is not interfered with by interposing 
non-magnetic substances, such as paper or wood, between the 
magnet and the body it attracts. 

If a magnetic needle be suspended by a silken thread, so as 
to be free to move, it will place itself in a longitudinal direction 
in regard to the earth ; one end pointing to the north and the 
other to the south. The north pole of the magnet is represented 
by the plus sign ( + ), and the south pole by the minus sign 
( — ). When two magnets are brought near together, it will 
be observed that the north pole of one attracts the south pole 
of the other; while poles of the same name repel. It is impos- 



ELECTRICAL ENERGY - 51 

sible to separate the poles by breaking the magnet into two equal 
parts, for when it is broken, each piece becomes a complete 
magnet, having a north and a south pole of its own, however 
often we may repeat the subdivision. 

ELECTRICITY. 

When glass or sealing wax is rubbed with a dry cloth, the 
glass and wax acquire the power of attracting small bits of 
paper or feathers. These bodies, when brought into this condi- 
tion, are said to be electrically excited. If a bit of feather be 
suspended by a fine silken thread and a piece of excited wax 
brought near, it will be attracted strongly by the wax and 
adhere to it for a moment, and then be repelled. This is due 
to the fact that the wax causes in the feather an electrical con- 
dition opposite to that of its own by induction, and the attrac- 
tion follows. When the two bodies come in contact the kind of 
electricity contained in the wax is transmitted to the feather, 
and both having the same kind of electricity, they repel each 
other. If the feather, after having been charged with elec- 
tricity from the wax, be brought near the excited glass, it 
will be attracted with much greater power than had the 
feather not been previously charged. These two kinds of elec- 
tricity — that excited in glass and that excited in wax — are dis- 
tinguished by calling the former positive, or vitreous, and the 
latter negative, or resinous. Two bodies charged with different 
kinds of electricity attract each other, but when they are simi- 
larly electrified they repel. 

A body containing a charge of electricity has the power to 
disturb the electrical condition of surrounding objects by the 
process of induction. When two bodies are brought near 
together, and the first is given a charge of positive electricity, 
the electrical condition of the second is disturbed in such man- 
ner that the side next to the charged body contains negative 



52 TEXT-BOOK OF CHEMISTRY 

electricity, while positive electricity is driven to its other ex- 
tremity. If the two bodies be now separated, the electrical 
disturbance in the second disappears ; but if, instead of separat- 
ing them, we make a momentary connection of the distant end 
of the second body with the earth, and thus allow its positive 
electricity to escape, it becomes charged with negative elec- 
tricity. If the two bodies are separated after allowing the sec- 
ond to acquire a charge of negative electricity, the charge is 
retained; but if the two be brought in contact, the negative 
electricity of one neutralizes the positive electricity of the other, 
and electrical equilibrium is established in them both. 

There is much resemblance between magnetism and elec- 
tricity in the properties of attraction, repulsion and induction; 
but in addition to these, the phenomenon of discharge is ob- 
served in electrical processes. Discharge is the act by which 
electricity is transferred from one body to another, in order to 
reestablish a condition of electrical equilibrium; it is often 
accompanied by the appearance of a bright spark, especially 
when opposed by conditions of resistance. Those materials 
which allow the free passage of electricity through their sub- 
stance are known as conductors, while those which oppose or 
obstruct its passage are called non-conductors, or insulators. 
Examples of the first class are represented by silver, copper 
and most of the metals ; examples of the second class are glass 
and rubber. Static electricity, is electricity at rest: dynamical, 
voltaic, or current electricity, is electricity in motion. 

ELECTRICITY BY FRICTION. 

The simplest form of the electrical machine, for producing 
electricity by friction, consists of a glass cylinder mounted upon 
an insulated frame. The cylinder revolves, by means of a crank, 
so as to rub against cushions of silk. The electricity is received 
upon the points of a copper comb, which convey it to a con- 
ductor of the same material. 



ELECTRICAL ENERGY 



53 



The newer and more powerful forms of machines for gen- 
erating static electricity are made so as to utilize the principle 
of induction. These are the Toepler-Holtz and the Wimshurst 
machines. The Wimshurst machine consists of two circular 
plates of glass, which revolve in different directions with equal 
velocity. Patches of tin-foil are placed upon the outer face of 

Fig. 22. 




Electrical Machine. (Bartley.) 

each plate at equal distances apart. Brushes of brass are so 
placed as to rub upon the face of the revolving glass plates, 
and the electricity generated is collected by horizontal brass 
combs, which convey it to the conductors. The machines are 
insulated by the use of glass stands, which prevent the escape 
of electricity. 

ELECTRICITY BY CHEMICAL ACTION. 

Electric Battery. When two solid bodies, conductors of 
electricity, are plunged into a liquid which acts unequally on 
them chemically, the electric equilibrium is disturbed; one be- 
coming positively, and the other negatively electrified. If a 



54 



TEXT-BOOK OF CHEMISTRY 



Fig. 23. 



strip of zinc and a strip of carbon be partly immersed in a glass 
vessel of dilute sulphuric acid, the zinc plate will gradually dis- 
solve and bubbles of hydrogen gas will escape from its surface. 
If, however, the two plates be connected by means of a copper 
wire, the hydrogen will cease to escape from the zinc plate and 
come off from the carbon plate. If the connecting wire be cut, 
and the two ends be placed on the tongue, a tingling sensation 
is produced ; and if we bring the free ends together, so that they 

touch, minute sparks will be 
observed, and a crackling 
sound will be noticed. These 
phenomena, noticed in the 
connecting wire, are due to 
the passage of an electric cur- 
rent; and the arrangement 
described is known as a gal- 
vanic battery, or a simple vol- 
taic element. Here we have 
a disturbance of electrical 
equilibrium by the chemical 
action in the battery cell, and 
an effort to reestablish equi- 
librium by a current in the 
connecting wire. The zinc 
plate in the battery generates 
positive electricity, the carbon plate, negative ; but positive elec- 
tricity accumulates at the carbon or negative plate, and negative 
electricity accumulates at the zinc or positive plate, so that out 
of the battery the electrode from the zinc carries negative elec- 
tricity, and the one from the carbon carries positive electricity. 
The wire coming from the carbon plate is called the positive 
electrode, or anode; from the zinc, the negative electrode, or 
cathode. The direction of the current is that which is taken 







Battery Cell. 



ELECTRICAL ENERGY 



55 



by the positive electricity, and the parts through which the 
current is flowing are known as the circuit. When the con- 
necting wires from the two plates of the battery are brought 
together, so that the current is free to flow, the circuit is said 
to be closed ; when they are disconnected, it is said to be open. 



Fig. 24. 



ELECTRICITY BY MAGNETIC INDUCTION. 

Electro-magnetism. It has long been known that mag- 
netism can be induced in steel articles by electrical discharges, 
but the meaning of these phenomena were not understood until 
they were investigated by Oersted and Ampere. If a wire con- 
veying an electrical current be brought near a magnet which 
is suspended in such a manner as to be free to move, and the 
current be passed over the magnet from north to south, the 
latter will deviate from its normal position toward the east. 
If the current be reversed, the 
magnet will deviate toward the 
west: placing the current below 
the magnet produces a deviation 
in the opposite direction to that 
which it produces when placed 
above. When the current is 
made to pass around the magnet 
in a longitudinal direction, of 
course the effect produced is 
much greater. In view of these facts, a magnet may be used 
not only to indicate the presence of a current of electricity, but 
also to indicate its direction. 

Action of the Magnet on the Electrical Current. If a cur- 
rent be passed through a movable wire and a stationary magnet 
be placed under the wire, the wire will turn and place itself at 
right angles to the magnet. When this movable wire is placed 
in a direction north and south with reference to the earth, and 




Action of Electrical Current on 
Magnet. (Bartley.) 



56 



TEXT-BOOK OF CHEMISTRY 



the current passed through it in the same direction, the mag- 
netism of the earth will cause it to arrange itself in a direction 
east and west; or at right angles to a line passed through the 
poles — the earth being a large magnet. 

Mutual Action of Electric Currents. If two wires trans- 
mitting an electric current be placed side by side, they will 
attract each other if the currents are passing in the same direc- 
tion ; if in opposite directions, they will repel. 



Fig. 



25. 




Magnetic Behavior of an Electrified Wire Coil. 

The Cause of Magnetism. If the wire be arranged in the 
form of a coil or helix, the coil will place itself in a direction 
north and south, with the direction of the current in the lower 
horizontal part from east to west, and thus we have an elec- 
trical magnet made of wire. 

In view of these facts, magnetism is supposed to be due to 
the presence of electrical currents circulating in the magnetic 
body in a direction at right angles to its long diameter, or 
around its long axis ; in the same manner that it is apparent in 
the wire coil, or helix. These currents pass in the magnet in 
the direction of the hands of a watch, when viewed at the south 
pole. 

Electromagnets are formed by winding an insulated wire 



ELECTRICAL ENERGY 



57 



many times around a piece of steel or soft iron, in a spiral man- 
ner, and passing a current of electricity through the wire. 
Magnetism induced in steel in this manner is permanent, and 
remains when the steel is withdrawn from the wire: in soft 
iron it is temporary, and ceases when the current stops. 

The strength of an electromagnet is dependent upon the 
length of the wire wound around it, and the strength of the 
current : by using a long wire and a powerful current, magnets 
of great strength can be made. 

Electricity Produced by Magnetism. If two wires be 
placed side by side, in a parallel manner, and a current of elec- 
tricity be passed through one of them, a current is also' momen- 
tarily induced in the second wire at the moment it starts in the 
first, passing in the opposite direction : when the current ceases 
in the first wire, a current is again induced in the second, 
passing in the same direction. The induced currents re- 
ferred to, have a moment- 
ary duration, appearing 
in the second wire when 
the current begins and 
when it ends, in the other 
wire. In view of these 
facts it can be readily 
seen that the conditions 
necessary for producing 
a current of electricity re- 
side in the magnet, and 

indeed, if a magnet be i nduction of a Current in a Parallel 

inserted within a coil of wire. (Bartiey.) 

wire, a current is induced in the wire, for a moment: again, 
when the magnet is withdrawn, a current passes in the wire 
in the opposite direction. If, by some mechanical contrivance, 
the magnet be rapidly inserted and withdrawn from the wire 




58 TEXT-BOOK OF CHEMISTRY 

coil, a rapidly alternating current will be set up in the wire. 
The equivalent of this may be accomplished in the following 
manner : A piece of soft iron, in the shape of a horse-shoe mag- 
net, is wrapped many times with a coil of insulated wire. A 
permanent magnet is made to revolve before the ends of the soft 
iron, so that its poles touch the latter with each revolution. By 
this means the soft iron is rapidly magnetized and demagnet- 
ized, and with each revolution, alternating currents are set up 
in the wire coil, which may be conducted through wires leading 
from the extremities of the coil. It is upon this principle that 
dynamos are constructed, for the conversion of mechanical into 
electrical energy. 

HEATING, LIGHTING AND CHEMICAL ACTION OF ELECTRICITY. 

The chief difference between the effects of frictional and 
voltaic electricity depends upon a difference in tension, and 
amount of the current, in the two cases. Frictional electricity 
has a very high tension, but the quantity is comparatively small ; 
voltaic electricity is of low tension and great quantity. 

Frictional electricity produces very great physiological and 
mechanical disturbance, but voltaic electricity acts in a mild and 
continuous manner. The electrodes from a number of voltaic 
cells may be held in the hands without producing other effects 
than mild stimulation of the nerves, and slight muscular con- 
tractions. 

The Heating and Lighting Effects are obtained by inter- 
posing resistance in the circuit. A wire, of good conducting 
material and of ample size, will carry a current without appre- 
ciable elevation of temperature; but if it be a poor conductor, 
and of small size, the temperature is raised, and the wire may 
become luminous from heat. A thin wire of platinum or iron 
may be easily fused by the passage of a strong current. The 
current passed through a filament of carbon, placed in a vacuum 



ELECTRICAL ENERGY 



59 



Fig. 2T. 



to prevent oxidation, gives the ordinary incandescent electric 
light. 

Whenever the current is broken, as by cutting a wire carry- 
ing the current, the electrical spark makes its appearance; and 
again, when the ends of the wires are brought together, this 
bright light is produced. In the electric arc-light, a current is 
passed through electrodes of dense carbon, which are separated 
by a short interval. In this case, the electric spark is con- 
tinuous, being formed between the electrodes. 

Electrolysis. That electricity is capable of exciting chemi- 
cal action, can be easily shown, by passing the current through 
water which has been slightly acidified with sulphuric acid. 
Under these conditions, the water is decomposed into its ele- 
ments; hydrogen coming off at the electro-negative pole, and 
oxygen at the electro-positive 
pole of the battery. The de- 
composition of a substance in 
this manner is known as elec- 
trolysis. Since pure water can- 
not be decomposed by the cur- 
rent, the theory of electrolysis 
assumes that action takes place 
through the acid in the fol- 
lowing manner : Sulphuric acid 
is decomposed into two parts, 
i. e., H 2 and S0 4 , called "ions." 
The electro-positive ion, H 2 , es- 
capes at the negative pole ; and 

the electro-negative ion, S0 4 , passing to the positive pole, 
liberates its charge, takes up H 2 from water to reproduce sul- 
phuric acid (H 2 S0 4 ) and thus sets oxygen (O) free. The 
current is capable of decomposing many other salts in solution 
in the manner described. The salt is broken into two parts 




Electrolysis of Hydrochloric 
Acid. 



60 TEXT-BOOK OF CHEMISTRY 

called ions, one of which goes to each pole, or electrode of the 
battery. 

Since only those substances which are capable of forming ions 
are conductors of electricity in solution, it is assumed that there 
is a temporary dissociation of most salts when they are dis- 
solved in water. Thus, in a solution of sodium chloride, it 
is assumed that there are ions of sodium and ions of chlorine, 
each capable of bearing its charge of electricity. In electrolysis 
of solutions of metallic salts, the electro-positive ion usually 
consists of the metal, and this is deposited on the electro-nega- 
tive pole. The process of electro-plating depends upon this 
action. The substance to be plated is attached to the negative 
pole, and, when the current is passed, it gradually becomes 
covered with a deposit of the metal. When the positive elec- 
trode is made of the same metal as that which is being deposited, 
it is slowly dissolved and maintains the strength of the solution. 

ELECTRICAL UNITS. 

The Ohm. All bodies offer resistance to the passage of an 
electrical current : even good conductors show this property to 
some extent. In order to give expression to this fact, the term 
" ohm " is employed, and it represents the unit of resistance. 
The ohm is a term used to denote the amount of resistance 
afforded to the current by a column of mercury having a cross- 
section of one square millimeter, and a length of 106.28 centi- 
meters, at the temperature of o° Centigrade. For practical pur- 
poses coils of wire, having a known resistance, called resistance 
coils, are employed. 

The Ampere is used to denote quantity of current. It is 
determined by noting the quantity of copper separated from a 
solution of copper sulphate, in a given time, when the current 
passes through. One ampere of current will deposit 0.327 
milligrams of copper per second. The quantity of current is 



ELECTRICAL ENERGY 6 1 

sometimes estimated by the amount of hydrogen and oxygen 
separated from water in a given time. 

The Volt is the unit of electro-motive force, electrical ten- 
sion, or power. The volt is the pressure required to maintain 
a current of one ampere through a resistance of one ohm. 

Ohm's Law expresses the relation existing between the three 
units. It is this : The strength of the current is equal to the 
electro-motive force divided by the resistance. 

The three electrical units are named after three great elec- 
tricians — Ohm, Ampere and Volta. 



PART II. 



CHEMICAL PHILOSOPHY. 

DISTINCTION BETWEEN PHYSICAL AND 
CHEMICAL ACTION. 

While it is difficult to define with exactness those phenomena 
which we class as physical, when distinguished from those 
termed chemical, it is easy to get a clear idea of the two De- 
reference to a typical example of each. The effect of heat upon 
many different substances furnishes abundant illustration of 
the two kinds of action. 

A piece of ice when heated is converted into water and then 
into steam, and when the heat is withdrawn the reverse of these 
changes takes place, resulting in the re-formation of ice. All 
such changes as these are of a temporary character, and do not 
affect the essential nature of the material in which they occur; 
they are referred to as physical changes, and they take place as 
a result of changes in the relationship of the molecules of the 
substance. 

In other cases, heat causes a different kind of change to take 
place in matter. The chlorate of potassium when heated in a 
test-tube is completely destroyed, so that two new bodies make 
their appearance, one of which is a gas and the other a solid, 
each different from the original substance, and remaining dif- 
ferent even when cooled. This permanent change, affecting 
the essential nature, as well as the properties of matter, occurs 
as the result of chemical action. 

The effects of heat upon potassium chlorate give rise to the 

63 



64 TEXT-BOOK OF CHEMISTRY 

kind of chemical action that results in decomposition. Chemi- 
cal action also takes place when we mix finely powdered iron 
and sulphur, and then heat the mixture. The action here is 
so violent that heat and light are given off, and when it is over 
the resulting mass is found to be a new substance, differing 
from both iron and sulphur in its properties. The new sub- 
stance, formed by union of iron and sulphur, is called iron sul- 
phide, and the unaided senses give us no evidence whatever 
that it contains either iron or sulphur. It is thus seen that 
chemical action results in the combination of substances and 
the formation of new bodies, as well as in their decomposition. 
For these reasons, we may say of chemical action, that it is 
different from all the other forms of energy, in producing an 
entire change in the essential nature and properties of the bodies 
upon which it acts. It results from changes in the relationship 
of certain small particles of matter called atoms. 

ELEMENTS AND COMPOUNDS. 

A further study of the effects of chemical action upon matter 
will bring clearly before the mind the fact that all of the ma- 
terial bodies of the universe may be placed in one or the other 
of the two great classes. These two classes comprise sub- 
stances known as elements, on the one hand, and compounds, 
on the other. 

Compounds. By heating the oxide of silver in a crucible 
to a high degree (about 250 ) it is resolved into two new sub- 
stances. One of these is a colorless gas, called oxygen; the 
other is a bright metal, silver. It is evident, from this experi- 
ment, that the oxide of silver in disappearing and being con- 
verted into the two new bodies, has been the subject of a chem- 
ical change, and we speak of the oxide by saying it is a 
compound. A compound is a body which, by chemical action, 
can be resolved into new substances that are unlike in their 



LAWS GOVERNING CHEMICAL ACTION 6$ 

properties. In other words, we say that a compound is a sub- 
stance which can be broken up into simpler forms of matter. 

Elements. If now, we proceed further with our investiga- 
tions, by attempting to simplify or decompose each of the bodies 
produced in the above experiment, we shall discover a different 
kind of substance from that which has been described as a com- 
pound. Neither the oxygen nor the silver will decompose or 
change into simpler forms, by any means whatsoever that are 
known at the present time. While it is possible to add some- 
thing to oxygen or to silver with which they each might unite ; 
it still remains a fact, that neither of these bodies can be broken 
up into simpler forms of matter. Such bodies as oxygen and 
silver are, therefore, called elements. An element is a sub- 
stance which cannot, by any of the means at present known, be 
broken up into simpler forms of matter. 

The number of elements at the present time is said to be about 
seventy-eight, but the number is constantly changing. This is 
due to the fact that some substances which were thought to be 
elements, have subsequently been decomposed, and thus been 
found to be compounds ; and furthermore, assiduous investiga- 
tors, from time to time, discover a new element, which is duly 
added to the list. 

LAWS GOVERNING CHEMICAL ACTION. 

Having directed our attention first to the quality of the ma- 
terials upon which chemical action manifests itself, we shall now 
turn to the subject of quantity as regards these materials. After 
decomposing the oxide of silver into its elements, we shall find 
that the sum of the weights of the elements equals the weight 
of the oxide; furthermore, we shall find the same quantity of 
oxygen united with a given quantity of silver in every case of 
analysis of the oxide. 

In every attempt to form compounds, the elements will be 
6 



66 TEXT-BOOK OF CHEMISTRY 

observed to enter into chemical union in definite quantities by 
weight, and not in the accidental quantities that might happen 
to be mixed. These facts led to the discovery of the laws of 
chemical combination. 

A law is a statement of what has been found to be true in 
every case that has come under observation, and its statement 
implies that many cases have been studied. 

i. Law of Chemical Combination by Weight, Law of Defi- 
nite Proportions, or Constancy of Composition: Each pure com- 
pound substance invariably consists of the same constituents 
united in the same proportions by weight. 

This law may be explained by saying that a given compound 
when analyzed is always found to have the same composition. 
For example : Calcium carbonate has of calcium, 40 parts ; of 
carbon, 12 parts ; of oxygen, 48 parts. When these ingredients 
are found combined in any other proportions they constitute an 
entirely different substance. 

2. Law of Multiple Proportions: When two elements are 
found to unite with each other in more than one proportion, to 
form, separate and distinct compounds, to a constant quantity 
of one element the quantities of the second bear a simple multi- 
ple relation to each other. 

In order to make the law clearer, let it be assumed that A 
and B combine in more than one proportion to form separate 
compounds. In one of the compounds there is found one part 
of A to one part of B ; in another, one part of A to two parts 
of B ; in still another, one part of A to three parts of B, etc. 
Thus, carbon monoxide consists of carbon, 12 ; of oxygen, 16 
parts ; obeying the first law. But there is another compound of 
carbon and oxygen which contains to 12 of carbon, twice 16 of 
oxygen or 32 of oxygen. If there be an excess of oxygen after 
forming the higher compound, it does not combine, but remains 
mixed with the carbonic oxide. If there be not enough of 



THE ATOMIC THEORY 6/ 

oxygen to convert all the carbon into higher oxide, the lower 
oxide is produced and such part of the latter is converted into 
higher oxide, as will satisfy the excess of oxygen present, and 
the two compounds remain mixed. 

3. Lcroj of Chemical Combination by Volume, Law of Gay- 
Lussac: When two or more gaseous elements combine chem- 
ically to form a gaseous compound, the volume of the individual 
constituents bears a simple relation to the volume of the com- 
pound formed. 

Applications of this law can be seen in the following ex- 
amples. One volume of hydrogen combined with one volume 
of chlorine, form two volumes of hydrochloric acid gas. Two 
volumes of hydrogen and one volume of oxygen form two 
volumes of steam. In other words, the relation between the 
volume of the compound and the volume of each of its constit- 
uents can be expressed by simple integer numbers, or whole 
numbers. 

THE ATOMIC THEORY. 

The discovery of a law naturally leads to a desire for an ex- 
planation. The question arises, Upon what condition is the ex- 
istence of this law dependent? In answer to this question an 
explanation is given which is called an hypothesis. If the hy- 
pothesis is capable of offering a satisfactory explanation of all 
the facts, and nothing can be discovered of a contradictory 
nature, it then becomes a theory. The atomic hypothesis, pro- 
posed by Dalton soon after he discovered the law of multiple 
proportions (1804), has answered all the requirements. 

Atoms. For each element a definite number may be selected, 
and these numbers, or multiples thereof, represent the propor- 
tions by weight in which the elements enter into chemical com- 
bination. The only explanation that can be offered to account 
for these facts is to assume that the elements combine by the 
union of minute particles of definite weight. These small par- 



68 TEXT-BOOK OF CHEMISTRY 

tides of matter are called atoms. An atom, therefore, is a 
particle of matter so small as to be incapable of division by the 
ordinary physical or chemical methods, 1 and it represents the 
unit of matter in chemical changes. The properties of atoms 
are weight and chemical affinity. Chemical affinity is the force 
of attraction exerted by atoms upon each other, and differs from 
all other forms of energy in producing an entire change in the 
nature and properties of the bodies upon which it acts. 

Molecules. On account of the force of attraction exerted 
between atoms they are nearly always found united in groups 
of two or more; in elements they usually link themselves to- 
gether in pairs, the atoms being of the same kind; in com- 
pounds they are united in varying numbers of different kinds. 
The groups of atoms formed by such unions are called mole- 
cules (a little mass). A molecule may be further defined by 
saying, It is the smallest particle of matter which can exist in 
a free or uncombined state. 

MOLECULAR CONSTITUTION OF GASES. 

The doctrine that heat is the result of molecular motion is 
generally conceded at the present time. Observations upon 
gases, and liquids as well, go* to show that the small particles, 
or molecules, of which they are composed are in a constant state 
of movement or agitation. With increase of temperature this 
molecular motion is greatly increased, and with reduction of 
temperature it is correspondingly retarded. At the temperature 
of absolute zero (273 below o° C.) it ceases altogether. 

The direction of motion in a molecule is that of a straight 
line until it meets with some modifying condition, such as com- 

1 Recent discoveries in regard to the properties of radio-active bodies 
indicate that their atoms are undergoing constant disintegration, and 
our ideas respecting the divisibility of atoms have to be modified ac- 
cordingly. See " Radium." 



MOLECULAR CONSTITUTION OF GASES 69 

pact with a fellow molecule or the sides of a containing vessel. 
The pressure of a gas is assumed to be due to the impacts of 
its molecules upon the sides of the containing vessel. Any 
means, therefore, by which the velocity of molecular motion 
is increased will increase the pressure. Thus it is observed that 
with an increase of temperature there is a corresponding in- 
crease in pressure, in a given volume of gas. Likewise, if a gas 
be made to occupy less volume, its molecules are forced closer 
together, and the number of impacts is correspondingly greater, 
giving increase in pressure (Boyle's Law). In equal volumes 
of different gases, under the same conditions of temperature and 
pressure, the number of impacts of molecules upon the sides of 
the vessels must be the same in each case. Since the total num- 
ber of impacts, under the same physical conditions, must be 
proportional to the total number of molecules present, it is 
safe to assume that the number of molecules is the same in 
equal volumes. These facts are stated in the Law of Avogadro: 
Equal volumes of gases, under similar conditions of tempera- 
ture and pressure, contain the same number of molecules. 

The great value of this law is dependent upon the fact that 
it gives the means of making a direct comparison of the weights 
of different molecules. If we take equal volumes of two gases, 
under the same physical conditions, we have equal numbers of 
molecules. The relation of the number of molecules in the two 
cases is as one is to one, and a direct comparison of their weight 
can be made. 

The behavior of gases in process of chemical union, as set 
forth in the law of Gay-Lussac, when viewed in the light of 
Avogadro's law, will give a clearer meaning to the terms atom 
and molecule. One volume (one molecule) of hydrogen will 
unite with one volume (one molecule) of chlorine to form two 
volumes (two molecules) of hydrochloric acid. Each volume 
(molecule) of hydrochloric acid contains a particle of hydro- 



yO TEXT-BOOK OF CHEMISTRY 

gen, obtained from one volume (molecule) of hydrogen; there- 
fore, we are forced to believe that the molecule of hydrogen is 
made up of two atoms. Each volume (molecule) of hydro- 
chloric acid contains also a particle of chlorine, obtained from 
one volume (molecule) of chlorine; showing that the molecule 
of chlorine is likewise made up of two atoms. 

When we weigh equal volumes of two gases we are weighing 
equal numbers of molecules. Hydrogen gas is taken as the 
standard in expressing the density of a gas, but since it has been 
shown that the molecule of hydrogen is made up of two atoms, 
its molecular weight is taken as equal to two. The molecular 
weight of any gas is therefore twice its density as compared with 
hydrogen. The density of nitrogen is 14, its molecular weight 
is 28 : the density of oxygen is 16, its molecular weight is 32 : 
the density of carbon dioxide is 22, its molecular weight is 44. 

One liter of hydrogen at o° and 760 m.m. pressure, weighs 
.0896 gram, and is called a crith; a unit used in calculating gas 
volume from weight. 

ATOMIC WEIGHT. 

As far as the absolute weight of atoms is concerned, we know 
nothing more than we do of their size, but it is a law of nature 
that all matter possesses weight, and if this is true of masses 
of matter it must also be true of the particles which compose 
these masses. As atomic weights express the proportions by 
weight in which the elements combine with each other, the 
weights in which two masses enter into combination will express 
the relation between the weights of their atoms ; presuming that 
the atoms link themselves together in pairs. The unit of com- 
parison for atomic weights is hydrogen, the lightest known sub- 
stance. For example, hydrogen will combine with chlorine in 
the proportion of one grain of the former to 35.4 grains of the 
latter. These numbers express their atomic weights. Atomic 



QUANTIVALENCE - J I 

weight, then, is the weight of an atom of an element expressed 
in terms of the hydrogen atom. The weights of the same kinds 
of atoms are always the same. The weights of atoms of dif- 
ferent kinds of elements are proportional to the combining 
weights of these elements, *. e., hydrogen, I ; sodium, 23, etc. 

Atomic Weight and Gas Volume. If equal volumes of dif- 
ferent elements, in the form of gas, under the same conditions 
of temperature and pressure, be weighed, these weights will be 
proportional to the atomic weights of the elements. We have 
already seen that equal volumes of gases, under the same phys- 
ical conditions, contain the same number of molecules. Since 
it has been shown that the molecules of gaseous elements con-' 
tain two atoms, the relation between volume and atomic weight, 
above stated, becomes clear. If we take a volume of hydro- 
gen which weighs 1, an equal volume of nitrogen will weigh 14, 
of oxygen 16, of chlorine 35.4, all of which quantities represent 
the atomic weights of the elements named. Some elements, 
whose molecules contain one, or more than two atoms, show 
an exception to this rule. 

The molecular weight of the elements is twice the atomic 
weight, with some few exceptions. In the case of phosphorus 
and arsenic, whose molecules contain four atoms, the weight is 
four times the atomic weight : in the case of cadmium and 
mercury, whose molecules contain one atom, it is the same as 
the atomic weight. The molecular weight of any substance 
may be said to be equal to the sum of the weights of the atoms 
in its molecule, or (with the exceptions noted) twice its den- 
sity when in the form of gas. 

QUANTIVALENCE, ATOMICITY, OR VALENCE. 

By quantivalence is meant the combining power, or value, of 
one atom in relation to another, expressed in terms of the hydro- 
gen atom. All atoms do not possess the same power of com- 



J2 TEXT-BOOK OF CHEMISTRY 

bining. Sometimes one atom will completely satisfy the affin- 
ities of another, but in other cases one atom requires several 
others to supply its needs. An atom which requires four other 
atoms to satisfy its chemical affinity, is said to have four times 
the value of each of the others. The atom of hydrogen is said 
to be univalent, and is the standard of comparison. When an 
element requires a single atom of hydrogen to satisfy its chemi- 
cal affinity, the former is said to be univalent or a monad; 
when it requires two, it is said to be bivalent, or a diad ; when 
it requires three it is trivalent, or a triad; when four, quad- 
rivalent, or tetrad, etc. Quantivalence is expressed by Roman 
numerals, placed to the upper right-hand side of the symbol, 
thus: 

H 1 , O n , N in , C IV , S n , P m , CI 1 , Br 1 , I 1 , etc. 

Quantivalence is also written by strokes of the pen, thus : 

H', CT, N'", S", P"', C"", CI', Br', etc. 

While quantivalence is a sufficiently constant property to be 
assigned to each atom, it is not unvarying. An atom, which 
under usual conditions acts as a triad, is designated as such; 
but the same atom may under other conditions act as a pentad. 
Another atom, which is usually bivalent, may under other con- 
ditions act as a quadrivalent, or even as a sexivalent atom. 
Quantivalence, as shown in these instances, usually varies by 
two units or points of attraction, an atom being one, three, and 
five valued ; or two, four, and six valued, etc. 

CHEMICAL SYMBOLS AND EQUATIONS. 

In making a record of the results of a chemical reaction, it 
would be exceedingly cumbersome and laborious to write out 
the name of each element concerned, and the nature of the 
changes they undergo. The necessity for a brief method of 



CHEMICAL SYMBOLS AND EQUATIONS 73 

writing the names of elements and compounds, and of record- 
ing their reactions, has resulted in the employment of symbols, 
formulas, and equations. 

A Symbol consists, usually, of the first letter of the Latin 
name for the element. In some cases, however, the names of 
several elements begin with the same letter; as carbon, chlorine 
and calcium. In such cases, the first letter of the Latin name 
is assigned to the most important, or the one which has been 
known the longest, the others being indicated by the first and 
some other letter. Carbon is indicated by the symbol, C; 
chlorine by the symbol, CI ; and calcium by Ca. 

A symbol is the first, or the first and some other letter, of 
the Latin name for the element. It represents the name of the 
element, a single atom of the element, its atomic weight, and one 
volume in the form of gas. If it be desired to indicate more 
than one atom of an element, this is done by the use of a small 
numeral, placed to the lower right-hand side of the symbol. 
Two atoms of each of the elements are indicated in the fol- 
lowing : 

G, H 2 , 2 , N 2 , S 2 , P 2 , Fe 2 . 

A Formula is a collection of symbols, and is intended to rep- 
resent a molecule. A formula represents the name of the mole- 
cule, the molecular weight, and two volumes of the substance 
when in the form of gas. 

A formula is multiplied, so as to indicate more than one mole- 
cule, by placing a full-sized numeral to the left-hand side. A 
molecule of hydrochloric acid is represented by the formula, 
HC1 ; two molecules of hydrochloric acid, by the formula, 2HCI, 
etc. It sometimes becomes necessary to indicate some multiple 
of a group of atoms in a molecule. Thus, the compound am- 
monium sulphate contains two of the group NH 4 united to the 
group S0 4 ; this fact is represented by the use of brackets, in 
this manner: (NH 4 ) 2 S0 4 . Two molecules of ammonium sul- 



74 TEXT-BOOK OF CHEMISTRY 

phate are represented by placing a full-sized numeral in front 
of that which stands for its molecule, thus : 2(NH 4 ) 2 S0 4 . 

An Equation represents a chemical reaction, and is composed 
of symbols and formulas. The formulas for the bodies en- 
tering into the reaction are placed to the left-hand side of the 
sign of equality, each being separated by the plus sign : the 
formulas for the bodies produced by the chemical reaction, are 
placed to the right of the sign of equality, also separated by 
the plus sign. The following equation represents the action 
of calcium carbonate upon hydrochloric acid, forming cal- 
cium chloride, water and carbon dioxide : 

CaCOs + 2HCI = CaCl 2 + H 2 + C0 2 . 

An equation not only serves to indicate the character of the 
substances entering into and formed by a reaction, but it rep- 
resents, as well, the quantity by weight of each substance con- 
cerned. If we bear in mind the functions of symbols, this can 
be easily understood. A symbol not only represents the name 
of the element and a single atom, but it also represents the 
atomic weight, or a quantity by weight proportional to the 
atomic weight. This being the case, the formula for calcium 
carbonate, CaC0 3 , stands for (Ca = 40) + (C= 12) + 
(0 3 = 48) = ioo, or 100 parts by weight of the carbonate. 
Therefore, we say, CaCO s = 100. (See table for atomic 
weights.) By a similar method we shall find that 2HCI = 72 ; 
CaCl 2 = 1 10 ; H 2 = 18 ; C0 2 = 44. 

The equation, written as follows, shows the quantities by 
weight of the different bodies entering into the reaction : 

100 + 72 =110 + 18+44. 
CaC0 3 + 2HCI = CaCl 2 + H 2 + C0 2 . 

Viewed in this light, the equation immediately becomes the 
basis for calculation of chemical quantities, furnishing all the 
factors necessary for such calculation. Take the example : 



CHEMICAL SYMBOLS AND EQUATIONS * 75 

How much hydrochloric acid is required to make 220 grams 
of calicum chloride? 

We see by the equation that J2 parts HC1 will give no parts 
CaCl 2 : 

Therefore : 

- L — X 220 = 144 gms. Answer. 

Another method is to form the equation : 
72: no:: at: 220. 

72 X 220 A 

x = = 144 gms. Answer. 

no & 

Example : How many liters of carbon dioxide can be ob- 
tained from 400 gms. calcium carbonate? 

100 gms. CaCOs form 44 gms. CO2, therefore : 
100 : 44 : : 400 : x. 
= 44X400 6 ca 

100 

The next step in the problem is to find how many liters of 
C0 2 are represented by 176 gms. The density of C0 2 is one- 
half its molecular weight, or 22, as compared with hydrogen. 
A liter of hydrogen weighs .0896 gm. ; therefore, a liter of C0 2 

would weigh : 

.0896 X 22 = 1. 97 1 2 gm. 

If one liter of C0 2 weighs 1.9712 gms., 176 gms. C0 2 would be 
176 



1.9712 



.28 + liters C0 2 . Answer. 



The branch of chemistry which relates to the calculation of 
chemical quantities is sometimes referred to as stoechiometry. 



J 6 TEXT-BOOK OF CHEMISTRY 

METHODS OF DETERMINING ATOMIC AND 
MOLECULAR WEIGHTS. 

The actual determination of atomic and molecular weights 
is a matter which does not greatly concern the student of med- 
ical chemistry ; he should, however, be conversant with the prin- 
ciples involved and the means by which the determinations are 
made. 

Both chemical and physical means are employed in these 
determinations. It is customary to apply several different 
methods to a single substance, each method, confirming the 
results of the others, ensures a correct result. 

Atomic Weights are determined: 

I. By chemical analysis, of a compound which contains the 
element whose atomic weight is to be determined united to one 
whose atomic weight is known. 

For example : Let it be desired to find the atomic weight 
of potassium in the compound, potassium chloride (KC1) ; the 
atomic weight of chlorine being known to be 35.5. 

Analysis of potassium chloride gives the percentage formula : 

Potassium 52.35% 

Chlorine 47-05 % 

100.00 

If we remember that the quantities by weight in which the ele- 
ments enter into combination are proportional to the weights 
of their atoms, assuming that they unite atom for atom, the 
following statement and equation hold true : 

The quantity of chlorine is to the quantity of potassium, as 
the atomic weight of chlorine is to the atomic weight of potas- 
sium. Let x represent the atomic weight of potassium. 

Therefore : 

47.65 : 52.35 : : 35.5 : x. 

v 52.35 X 35-5 
*" 47.65 = 39 < 



DETERMINING MOLECULAR WEIGHTS JJ 

This method alone is not conclusive, because it does not show 
how many atoms of each element enter into the compound. 
Further experiments are then made to confirm or deny these 
results. 

2. By replacement of hydrogen in a compound of known 
composition, by the element whose atomic weight is to be 
obtained. 

If in 36 gms. of hydrochloric acid, one gm. of hydrogen 
were replaced by 39 gms. of potassium, we would conclude 
that the atomic weight of potassium is 39. 

The same source of error enters here as in the first method, 
but the conclusions of this experiment are confirmed by taking 
the vapor density of potassium. 

3. By taking the vapor density of the element. 

It has been shown that the weight of equal volumes of the 
elements in form of gas are proportional to the atomic weights. 
The density of potassium vapor, as compared to hydrogen, is 
as 39 is to 1. Therefore, we have further evidence that the 
atomic weight is 39. 

4. By relation between specific heat and atomic weight. 
The fact that all atoms have the same capacity for heat is 

shown by the simple experiment of taking of the elements quan- 
tities by weight which are proportional to their atomic weights 
and heating them all alike. If we take 32 gms. of sulphur, 12 
gms. of carbon, 200 gms. of mercury, and 65 gms. of zinc, and 
subject them all to the same source of heat, the temperature of 
all will be found to be the same. This is a surprising fact, 
seeing that we have in these quantities such widely differing 
amounts of matter: the quantity of mercury being greatest; 
the quantity of carbon being least. 

The weights of the masses taken, however, are directly pro- 
portional to the atomic weights, and we have a right to assume 
that they represent approximately equal numbers' of atoms of 



7 8 TEXT-BOOK OF CHEMISTRY 

each element. These observations point out a relationship be- 
tween atomic weight and capacity for heat, in the elements, 
which has not hitherto been observed. This relationship can 
be more clearly expressed in terms which are set forth in the 
following table. The table shows that the specific heat of an 
element multiplied by its atomic weight gives a constant quan- 
tity which is 6.5, or a quantity closely approximating this 
number : 



:ment. 


Atomic Weight. 


Specific Heat. 


Product. 


Li - 


7 — 


•94 — 


6.6 


Na - 


23 — 


.29 — 


6-7 


Mg - 


24.4 — 


•25 — 


6.1 


K 


39 — 


•17 — 


6.6 


Ca - 


40 — 


•17 — 


6.8 



The specific heat of an element is inversely proportional to 
its atomic weight and, therefore, when multiplied by the atomic 
weight gives a constant quantity. By dividing 6.5 by the specific 
heat the atomic weight is obtained. These values are approxi- 
mate, and some elements show exceptions to this law. 

Molecular Weights are determined : 

1. By chemical analysis the percentage formula is determined, 
and by dividing the percentage of each element by its atomic 
weight the relative numbers of atoms in the molecule are found. 

Analysis of 100 parts of potassium chloride: 

K = 52 per cent, -r- 39 = 1.3 -\- : in simplest terms iK. 
CI = 48 per cent. -4- 35 = 1.3 + : i n simplest terms id. 

The results of this analysis show that the relative number of 
atoms of the elements is the same. The number of atoms of 
potassium bear a ratio to the number of atoms of chlorine that 
is expressed by the ratio of one to one. This analysis does not 
show the actual number of atoms present, but that may be 
determined by taking the vapor density. 

2. By ascertaining the vapor density of the compound as com- 
pared to hydrogen. 



DETERMINING MOLECULAR WEIGHTS 79 

The vapor density of a compound is one-half its molecular 
weight. If the vapor density be 37, the molecular weight would 
be 74; corresponding to the formula KG (K = 39+C1 = 
35 = KC1 = 74) . If the vapor density be 74, the molecular 
weight would be 148 ; corresponding to the formula, K 2 C1 2 = 
148. 

3. By the method of Raoult. 

Relations have been discovered between the freezing point 
of liquids and the molecular weight of dissolved solids. By dis- 
solving solid bodies in water the freezing point is reduced be- 
low o° C. If the solids be dissolved in quantities proportional 
to their molecular weights, the freezing point is lowered by an 
amount which is constant. For example : Assume that we have 
a number of bodies whose molecular weights are represented 
by the numbers 5, 10, 30 and 60. If we take 100 c.c. of water, 
in each of four vessels, and then dissolve the bodies in each in 
quantities proportional to' the molecular weight; that is, 5 gm. 
in one, 10 gm. in another, etc., the freezing point will be de- 
pressed to the same extent in all. Therefore, if it require ten 
per cent, of a salt whose molecular weight is known to reduce 
the freezing point i° C, and 20 per cent, of a salt whose molec- 
ular weight is unknown to reduce the freezing point i° C, 
the ratio between the molecular weights is as 10 to 20. 

Raoult's method is specially applicable to organic bodies, or 
to those which do not dissociate when dissolved. It is not 
applicable to all substances. 

4. Other properties are also made use of in determining 
molecular weight, such as similarity in properties between 
bodies of known and unknown molecular weight ; the property 
of forming similarly shaped crystals, etc. 

The weight of a molecule equals the sum of the weights of 
its atoms. 



80 TEXT-BOOK OF CHEMISTRY 



CONDITIONS INFLUENCING CHEMICAL 
CHANGES. 

Chemical action is induced by various forms of energy. Heat 
will decompose many compounds into simpler forms, or cause 
new combinations between elements and compounds. Light is 
a great factor in causing chemical action. Hydrogen and 
chlorine will combine ; the chemical changes taking place in the 
green parts of plants, by which energy is stored up ; decomposi- 
tion of salts of silver ; changes in many organic bodies, are all 
brought about by the action of light. Electricity causes chemi- 
cal action in the electrolysis of water ; the decomposition of 
salts in solution, in electroplating, etc. 

The conditions favoring action of chemical substances upon 
each other are those which bring the particles of matter in close 
and intimate relationship. 

Chemical action does not readily occur between solid bodies, 
and certainly never unless they are brought in very close con- 
tact, as by mixing powdered solids. In many cases powdered 
solids when mixed do not act upon each other unless they are 
moistened with a liquid in which they dissolve, or unless they 
are heated. 

Chemical action takes place more readily between liquids, 
or between solid bodies dissolved in a liquid. Here the particles 
are brought near together, and the molecules freely intermingle. 
For the same reasons, chemical action is greatly facilitated by 
the gaseous state where molecules are constantly coming in 
contact. 

Prediction of Chemical Reactions. No infallible rule can 
be laid down by which we can say in advance exactly what 
chemical change will occur under given conditions; this has 
to be determined in each case by experiment. 

The action of mass is a factor in determining chemical 



CONDITIONS INFLUENCING CHEMICAL CHANGES 8 1 

change, both as regards character and amount. For example: 
Oxygen will be removed from hot ferric oxide by passing a 
large quantity or mass of hydrogen over the heated oxide ; but 
oxygen will be taken from hydrogen by bringing water in con- 
tact with a mass of red-hot iron. In other words, oxygen in 
each case passes to the substance having greater mass; some- 
times favoring iron and sometimes favoring hydrogen. 

The action of sulphuric acid on sodium nitrate forms sodium 
acid sulphate and nitric acid, but a large excess of nitric acid 
will convert sodium acid sulphate into sodium nitrate and free 
sulphuric acid. 

We thus see that the character of chemical change is depend- 
ent upon the mass or quantity of matter entering into the 
reaction. 

The action of mass in regard to amount of chemical change is 
seen when two mixed bodies reacting chemically do not com- 
pletely decompose each other. Whenever an addition is made 
to the mixture of either of the two bodies, an additional amount 
of change occurs, though it may never be complete. The 
amount of chemical action is thus dependent upon the mass of 
reacting substances. 

The Laws of Berthollet predict in some measure the char- 
acter of a chemical change ; they are : 

i. When two or more compounds are brought together in 
solution, and are capable of forming an insoluble body, that sub- 
stance is formed and precipitated. 

2. When two or more compounds are brought together in 
solution, and are capable of forming a gaseous body, that body 
is formed and liberated. 

Catalytic action is the property possessed by some bodies 
by which they facilitate chemical change in other substances 
without undergoing any apparent change themselves. For ex- 
ample : Chemical change is facilitated in potassium chlorate, 
7 



82 TEXT-BOOK OF CHEMISTRY 

when this compound is heated to form oxygen, by adding black 
oxide of manganese. The black oxide of manganese undergoes 
no change itself, but by its presence facilitates change in the 
chlorate of potassium. It is very probable, however, that all 
bodies acting catalytically are decomposed and reproduced dur- 
ing the course of the reaction. 

Nascent state means the moment of birth, referring to the 
atom. The atoms of an element are in the nascent state when 
they are first liberated from combination and have not had 
time to unite into molecules. Nascent hydrogen is hydrogen at 
the moment of its liberation from union with another substance. 
An element in the nascent state is much more active and ready 
to form new combinations than at any other time, because its 
atoms are free and have not yet united with each other to form 
molecules. 

A Radical is an unsaturated group of atoms, which behaves 
in many compounds like a single atom. A radical, like an 
atom, is not usually found in the free state, but generally occurs 
linked to other radicals or atoms. The radical, NH 4 , is found 
in all the compounds of ammonium, and behaves like a single 
atom of a metallic element. 

Analysis means the breaking up or separation of compounds. 
Synthesis means the putting together or building up of com- 
pounds. A Chemical reaction is a chemical change, and it is 
usually brought about by the addition of a reagent. 

NOMENCLATURE. 

The names of compounds are generally descriptive of their 
composition or chemical structure, but it sometimes happens 
that a compound was named at a time when its chemical nature 
was not understood and such names do not give any idea of 
the nature of the substance. Many of the old names of com- 
pounds are retained to the present time. It is, therefore, diffi- 



CLASSIFICATION OF COMPOUNDS 83 

cult to give set rules for chemical nomenclature; a knowledge 
of this subject comes gradually as we proceed with our studies. 

The names of compounds formed by direct union of two 
elements usually end in ide, for example : N 2 0, nitrogen oxide. 
When the elements combine in more than one proportion the 
terms mono-, di-, tri-, tetra-, penta-, etc., are used to denote the 
different compounds, for example : N 2 0, nitrogen monoxide ; 
N 2 2 , nitrogen dioxide; N 2 3 , nitrogen trioxide, etc. When 
an element forms two classes of compounds the terms ons and 
kj are used to distinguish between lower and higher forms of 
combination, such as ferrous and ferric chloride. The prefixes 
mono- and proto- are used to indicate lower forms of combina- 
tion, and sesqui- and per- to indicate higher forms of combina- 
tion. 

Names of salts derived from acids having a single atom for 
their acidulous radical end in ide, that is, hydrochloric acid 
forms chlorides. Names of salts derived from acids whose 
names end in ons, end in ite, namely, sulphurous acid forms 
sulphites. Names of salts derived from acids whose names end 
in ic, end in ate, namely, sulphuric acid forms sulphates. 

In pronouncing the name of a compound the metallic or 
basylous radical precedes that of the acidulous. 

CLASSIFICATION OF COMPOUNDS. 

Compounds are classified : 

1. According to reaction, into acids, bases and neutral bodies. 

Acids, when soluble, usually have a sour taste; they contain 
replaceable hydrogen; they usually change the color of blue 
litmus to red. 

Bases, when soluble, have a taste of lye ; they replace hydro- 
gen in acids to form salts ; they change the color of litmus from 
red to blue. 



84 TEXT-BOOK OF CHEMISTRY 

Neutral bodies are those which do not possess the properties 
of either an acid or a base, and have no action upon litmus. 

Amphoteric reaction is a peculiar property observed in some 
bodies by which they turn blue litmus red and red litmus blue ; 
acting both as an acid and as a base. This peculiar property, 
is sometimes observed in the milk of carnivorous animals. 

Indicators are substances employed for the purpose of de- 
termining whether a given body is acid, basic, or neutral in re- 
action. Litmus and phenol-phthalein are the ones most com- 
monly used. Litmus is red in acid solution, blue in alkaline 
solution and is not affected by a neutral body. Phenol-phthalein 
is purplish-red in alkaline solution; it is colorless in acid or 
neutral solution. 

2. According to chemical composition. In a general sense, 
any chemical compound may be correctly called a salt. The 
term salt, in a more restricted sense, is applied to those bodies 
which are formed by replacement of the replaceable hydrogen 
in an acid by a base, or by union of acids with bases. Salts 
are said to be normal, bi- or acid, basic and double, according 
to their molecular composition. 

A normal salt is formed by replacement of all the replaceable 
hydrogen of an acid by a base. For example: Sulphuric acid 
contains two replaceable hydrogen atoms and when both of 
these are replaced a normal salt results. The formula for nor- 
mal sodium sulphate is Na 2 S0 4 . 

A bi- or acid salt is formed by replacement of part of the re- 
placeable hydrogen of an acid by a base. If in sulphuric acid, 
one atom of hydrogen is replaced by sodium, the bi- or acid sul- 
phate of sodium results, thus : NaHS0 4 . 

A basic salt contains more of the basic radical than is neces- 
sary to form a normal salt. An example of a basic salt is the 
basic lead nitrate, PbOHN0 3 . Another view of the structure 
of a basic salt is to assume that it is formed by replacement of 



THE ELEMENTS 85 

a part of the OH radical of a base by an acid radical. For ex- 
ample: The hydroxide of lead, a base, has the formula, 
Pb(OH) 2 ; if one of the two OH radicals in this compound 
be replaced by the radical of nitric acid, NO s , basic lead nitrate 
is formed, PbOHNO s . 

Double salts are formed in two ways : First, by replacement 
of the hydrogen of an acid by two different bases, thus : 
KNaS0 4 , potassium sodium sulphate. Secondly, by linking 
together of two molecules, thus : PtCl 4 2KCl, double chloride of 
platinum and potassium. 

Salts may have an acid, basic or neutral reaction, but basic 
salts usually have a basic reaction. 

THE ELEMENTS. 

Of the total number of about seventy-six elements known, 
only about one-third are of practical interest or importance. 
These important elements form the chief portion of the earth, 
contribute to the formation of plants and animals, and are used 
in various ways for the convenience and comfort of man. 

Some of the elements are of scientific interest only, and there 
is some doubt in regard to the elementary character of a few. 

Twelve elements enter into the composition of living beings 
without exception : hydrogen, oxygen, nitrogen, carbon, sul- 
phur, phosphorus, chlorine, potassium, sodium, calcium, mag- 
nesium and iron. In addition to the elements named, the fol- 
lowing are often present but are not always a part of the living 
body : iodine, bromine, fluorine, silicon, aluminum, manganese 
and copper. 

The elements are found in all three states of aggregation, 
but most of them are solids. Five of the elements are gases; 
hydrogen, oxygen, nitrogen, fluorine and chlorine : two of them 
are liquids ; bromine and mercury. Most of the solid elements 
are capable of being fused and volatilized by the action of heat. 



86 TEXT-BOOK OF CHEMISTRY 

Allotropic modification. In some few cases it has been found 
that an element is capable of existing in several dissimilar 
forms, for example: Carbon, which is usually seen as black, 
amorphous, solid charcoal, also occurs in the form of diamond, 
a beautiful, transparent crystal. This property of carbon, by 
which it occurs in these dissimilar forms, is called allotropism, 
and we speak of the diamond as an allotropic modification of 
carbon. Some important elements showing well denned allo- 
tropic forms are oxygen, phosphorus, arsenic and silver. 

CLASSIFICATION OF ELEMENTS. 

Early in the history of chemistry two distinct classes of ele- 
ments were recognized on account of difference in properties. 
Such bodies as iron, silver and lead, having a characteristic 
lustre and power to conduct heat were distinguished from sub- 
stances like sulphur, charcoal and phosphorus, which are devoid 
of these properties. Members of the first group are called 
metals, and members of the second group are called non- 
metals. 

Metals have metallic lustre, are good conductors of heat and 
electricity, and their oxides usually form basic substances. 

Non-metals do not have metallic lustre, are not good con- 
ductors of heat and electricity, and their oxides usually form 
acidulous radicals. 

While it is easy to distinguish a metal from a non-metal 
when a typical member of each group is taken, there are some 
elements which behave in a manner that places them in an 
intermediate position between the groups. Such elements as 
these act as metals under some conditions and as non-metals 
under others, but these instances are not numerous, and do not 
interfere with the value of the system of classification. 

Classification of Mendelejeff. This classification is based on 
the atomic weights of the elements. If. we examine the list of 



THE ELEMENTS 87 

elements we shall find that there are groups in which there is 
a direct relationship between atomic weights and properties. 
Among these may be mentioned lithium, potassium and sodium ; 
and chlorine, bromine and iodine. These elements arranged 
according to their atomic weights, appear as follows : 

Li —7, CI = 35, 

Na = 23, Br = 79, 

K = 39, I = 126. 

If in these groups the atomic weights of the first' and last 
members be added together and the sum divided by two, very 
nearly the atomic weights of the middle members are obtained. 
If we examine the properties of the members of each of these 
groups we shall find that they are very similar. Considera- 
tions of this sort have led to a careful study of the atomic 
weights and properties of elements to find if there is not some 
general relationship between these two factors, and it has 
been found that the connection stated above is much more gen- 
eral than was at first supposed. 

Mendelejeff first pointed out the fact that if the light ele- 
ments whose atomic weights range from 7 to 36 be arranged in 
the order of their atomic weights, they are also arranged in 
the order of their properties, as shown in the following: 

Li = 7 : Be = 9 : B = 11 : C = 12 : N = 14 : O = 16 : F = 19. 

Na = 23 : Mg = 24: Al = 27: Si = 28: P = 31 : S = 32: CI = 35- 

In these series it will be seen that there is a gradation of 
properties from left to right, the elements on the left being most 
basic, those on the right least basic : the power to combine with 
oxygen increases from left to right : the power to combine with 
hydrogen, being absent on the left, appears at the middle and 
increases towards the right. Elements which are similar in 
properties fall together, such as lithium and sodium, beryllium 
and magnesium, oxygen and sulphur, etc. 



88 TEXT-BOOK OF CHEMISTRY 

This system of classification has been found to apply to all 
the elements, and Mendelejeff has arranged them in the order 
of their atomic weights in periods of seven, the properties of 
the first element being found to be repeated in every eighth 
element. This classification is shown in the table on page 89. 

It will be noted in the table that the members of the even 
series resemble each other, and the members of the uneven 
series resemble each other more closely than do the members of 
the even and uneven series. In other words, members of series 
1, 3 and 5 are very much alike, and the same can be said for the 
members of series 2, 4 and 6. On the other hand, members of 
series 1 and 2, or 2 and 3, or 4 and 5 are not very much alike. 
It will be further seen that following the even series 4, 6 and 
10 there are groups of elements which hold an intermediate 
position and constitute an eighth group to themselves. 

A small period comprises a series of seven elements. A large 
period comprises an even and an uneven series with the inter- 
mediate group. 1 

1 The student will be better prepared to comprehend the full mean- 
ing of this system of classification after he has studied the properties 
of the different elements. 



MENDELEJEFF S TABLE. 



89 





2 i 




On 
to 






O 

Ph 


10 

1 5 

Ph 




O 


On 
10 


CO 
O 

^J 
Ph 


CO 

1 | 




0" 


P=h 


O 

Ph 


M 

On 

1 : 





t-H 0« 

>2 

O 


ffiO 


ON 


CO 

U 


10 O 

u^OO 

a* 


10 


1 1 

10 

& 1 


1 


d 

> 2 

O 


SO 


O 


CO 
Xfl 


ON 

O 


On <u 

oh 


00 
1 £ 


On 
CO 

O 


d 

O 






CO 

Ph 






On m 

1- 




1 


d 

SI 




u 


00 

C/3 


00 ^ 


00 

M 

ON fl 


6 I s 


M 

CO 

si 
H 


d 

O 


14 

1 O 


pq 


< 




CO 


ON M 

00 fl 


00 1 £cf 

-3 ^ 


| 


d 

HH 3 

hH O 

U 

O 


1 ° 


On 




O NO 
6 N 


00 rtf 


1 O 

ft 1 8 

cJ 1 Dh 

fq 1 * 


1 


d 
1—1 

6 


1 
1 s 


3 


co 


co 

ON^ 

CO ZS 


00 



»o 11 


1 *^ 

co 1 £ 

CO M 

U 1 


1 




be 
c 

■s'fl 

T3 In 

c l2 . 

5^ <« 

O ■" 1) 

Ett) K 


tn 

.SJ to 

w 

tn 

T3 

.2 l_l 

Ph 


1— 1 


CO Tt 

HH 
t— 1 


-5 -5 

> 

1— 1 


.a .£ £ £ 

Jt 00 OnO 

> 





9 o 



TEXT-BOOK OF CHEMISTRY 



Table of Elements. 



Symbol. 

Aluminum Al 

Antimony Sb 

Argon A 

Arsenic As 

Barium Ba 

Bismuth Bi 

Boron B 

Bromine Br 

Cadmium Cd 

Caesium Cs 

Calcium Ca 

Carbon C 

Cerium Ce 

Chlorine CI 

Chromium Cr 

Cobalt Co 

Columbium 2 Cb 

Copper Cu 

Erbium Er 

Fluorine F 

Gadolinium Gd 

Gallium Ga 

Germanium Ge 

Glucinum 3 Gl 

Gold Au 

Helium He 

Hydrogen H 

Indium In 

Iodine I 

Iridium Ir 

Iron Fe 

Krypton Kr 

Lanthanum La 

Lead Pb 

Lithium Li 

Magnesium Mg 

Manganese Mn 

Mercury Hg 

Molybdenum Mo 



Atomic 
Weight.* 

26.9 

H9-3 

39-6 

74-4 
136.4 
206.9 

10.9 

79-36 
in. 6 
i3i-9 

39-8 

11. 91 
139-2 

35-18 

5i-7 

S8.56 

93-3 

63.1 
164.8 

18.9 
155. 

69-5 

71.9 
9-03 
195-7 
4- 

1. 000 
113-1 
125.90 

I9I-5 
55-5 
81.2 

137-9 
205-35 
6.98 

24.18 

54-6 
198.5 

95-3 



Symbol. 

Neodymium Nd 

Neon Ne 

Nickel Ni 

Nitrogen N 

Osmium Os 

Oxygen O 

Palladium Pd 

Phosphorus P 

Platinum Pt 

Potassium K 

Praseodymium 4 ... Pr 

Radium Ra 

Rhodium . . ." Rh 

Rubidium Rb 

Ruthenium Ru 

Samarium Sm 

Scandium Sc 

Selenium Se 

Silicon Si 

Silver Ag 

Sodium Na 

Strontium Sr 

Sulphur S 

Tantalum Ta 

Tellurium Te 

Terbium Tb 

Thallium Tl 

Thorium Th 

Thulium Tm 

Tin Sn 

Titanium Ti 

Tungsten W 

Uranium U 

Vanadium V 

Xenon Xe 

Ytterbium Yb 

Yttrium Yt 

Zinc Zn 

Zirconium Zr 



Atomic 
Weight. 1 

142.5 
19.9 
58.3 

13-93 
189.6 

15.88 
105.7 

30.77 
193-3 

38.86 

139-4 
223. 
102.2 
84.8 
100.9 
148.9 
43-8 
78.6 
28.2 
107.12 
22.88 
86.94 
31.83 
181.6 
126.6 
158.8 
202.6 
230.8 

169.7 
118.1 

47-7 
182.6 

236.7 
50.8 

127. 

171.7 
88.3 
64.9 
89.9 



1 H=i.ooo (U. S. Pharmacopoeia, Eighth Decennial Revision) 

2 Also called Niobium, Nb. 

3 Also called Beryllium, Be. 

4 Also called Didymium, Di. 



PART III. 



INORGANIC CHEMISTRY. 

THE NON-METALLIC ELEMENTS. 

The number of the non-metals is about eighteen, but of 
these, helium, argon, selenium and tellurium are of little im- 
portance and will receive only a brief mention in this book. 

Most of the important non-metals are solids, one is a liquid 
and five are gases at the ordinary temperature. 

Non-metals do not possess metallic lustre, except iodine ; they 
are not conductors of heat or electricity; their oxides usually 
form acids ; they are electro-negative. 

HYDROGEN. 

Symbol, H. Atomic Weight, I. Ouantivalence, I. 

History. Hydrogen was prepared by Paracelsus in the 
sixteenth century, but its true character was. established by 
Cavendish in 1766, who found it to be a peculiar gas, and gave 
it the name " inflammable air." 

Occurrence in Nature. Hydrogen occurs in comparatively 
small amount in the free state, being found in the intestinal 
gases and in gases issuing from the earth. It occurs in abun- 
dance in combination in water, in the bodies of plants and 
animals, in ammonium compounds and in acids. 

Preparation. Hydrogen can be obtained in a pure state 
by passing a current of electricity through water which has been 
acidified with sulphuric acid. It can be prepared, also, by the 

91 



9 2 



TEXT-BOOK OF CHEMISTRY 



action of metallic sodium upon water, as shown in the equation : 



Na 

Sodium 



+ H 2 = NaOH + H. 

Water Sodium hydroxide Hydrogen 



The usual method of preparation consists in adding dilute 
sulphuric acid to fragments of zinc in a glass vessel, and allow- 
ing the gas to escape through a delivery tube, it is then col- 
lected over water. The reaction is represented by the following 
equation : 



Zn 

Zinc 



+ H 2 S0 4 = ZnSO* + H 2 . 

Sulphuric acid Zinc sulphate Hydrogen 



Hydrogen, and many other gases, are collected by taking a 
vessel, filling it with water and inverting it in another vessel 
filled with the same liquid. The delivery-tube, from which 



Fig. 28. 




Preparation of Hydrogen. 

hydrogen is escaping, is carried under the edge of the inverted 
vessel and the gas rises, displacing the water until a vesselful 
is obtained. When a gas to be collected is soluble in water, 
some other liquid is employed, such as mercury. 



THE NON-METALLIC ELEMENTS 93 

Properties. Hydrogen is a colorless, odorless, tasteless, in- 
flammable gas; it is the lightest known substance, being 14.4 
times lighter than air. One liter of hydrogen at o° C, 760 mm. 
mercury, weighs .0896 gm. ; this unit has been referred to as the 
crith. 

By compressing the gas to 180 atmospheres, cooling it by 
surrounding with liquid air boiling in a vacuum, and suddenly 
reducing the pressure to 40 atmospheres, hydrogen has been 
obtained as a transparent, colorless liquid. Certain metals, such 
as iron, platinum and palladium, when heated to redness, have 
the power to absorb large volumes of hydrogen, forming com- 
pounds which have some resemblance to alloys ; this property 
is referred to as occlusion. On account of the same property 
hydrogen is capable of passing through the substance of hot 
metals. 

Hydrogen burns in the air with production of a high degree 
of heat, with a non-luminous flame of slightly bluish color; it 
does not support combustion or respiration, but can be breathed 
without danger for a short time, imparting a peculiar piping 
tone to the voice. A mixture of air, or oxygen, with hydrogen 
will explode violently when ignited. The oxy-hydrogen flame 
is produced by combustion of a mixture of oxygen and hydro- 
gen in a peculiarly constructed burner, wherein the gases are 
brought together at the moment they undergo ignition. This 
flame is non-luminous and gives a high degree of heat: if it be 
caused to fall upon a mass of unslaked lime the latter be- 
comes incandescent, and emits the well-known " calcium light." 

Experiment. Place a few fragments of zinc in a large test-tube, add 
enough water to cover the zinc and then a few drops of sulphuric or 
hydrochloric acid. Fit a delivery tube, wait for air to be expelled and 
collect the hydrogen over water. 

Examine the gas and confirm the properties given above. Notice 
that the gas is combustible and not a supporter of combustion. Re- 
serve two small test-tubes full of the gas. Complete the equations : 

Zn + H 2 S0 4 = Zn + 2HCI = 



94 TEXT-BOOK OF CHEMISTRY 

How many grammes of hydrogen may be obtained from 50 grammes 
of sulphuric acid? How many liters? 

Water is produced by the combustion of hydrogen, and it 
can be collected in drops by holding a cold surface over the 
hydrogen flame. In its chemical relations, hydrogen shows 
some resemblance to metals, being found in all acids, and its 
place being substituted by a metal in forming a salt. 

OXYGEN. 

Symbol, O. Atomic Weight, 16. Quantivalence, II. 

History. Discovered by Priestley, in England, and Scheele, 
in Sweden, in 1774. Lavoisier, in France, first explained the 
chemical behavior of oxygen in reference to combustion and 
respiration. 

Occurrence in Nature. Oxygen is the most abundant ele- 
ment in nature; probably one-third of the weight of the earth 
is made up of this element. It occurs free in the air ; in com- 
bination, it occurs as a constituent of most mineral and organic 
bodies, and in water. 

Preparation. Oxygen can be made by heating the oxides 
of mercury, gold, silver or platinum, or by heating potassium 
bichromate with sulphuric acid. 

The usual method of preparation consists in heating to- 
gether potassium chlorate and black oxide of manganese, in a 
test-tube, to which a delivery tube has been fitted, and collect- 
ing the gas over water. If potassium chlorate be heated alone 
oxygen will be given off at a high temperature, but the chem- 
ical action is facilitated by the presence of black oxide of 
manganese, the gas coming off at a lower temperature. This 
is an instance of " catalytic action," the quantity of black oxide 
of manganese being the same before and after the experiment. 

Properties. A colorless, odorless, tasteless gas ; density six- 
teen times that of hydrogen; solubility in water, about three 



THE NON-METALLIC ELEMENTS 95 

volumes in ioo at ordinary temperature. A colorless liquid at 
temperature of — 140 and pressure of 300 atmospheres. Boils 
at — 180 at pressure of atmosphere. 

Chemically, oxygen is a very active element, and combines 
directly with nearly all elements except CI, Br, I, F, Au and 
Pt : it combines with these indirectly, except fluorine. The 
direct union of bodies with oxygen, with the evolution of heat 
and light, is called combustion. Oxidation of bodies in air 
without evolution of light is called slow combustion. Com- 
bustion in pure oxygen takes place with great intensity: the 
red-hot wick of an extinguished candle or a piece of glowing 
charcoal will burst into flame and burn with a brilliant light, 
when plunged into the gas. 

The union of oxygen with another body is called oxidation, 
and it is not always necessary for the oxygen to be in a free 
state, for some substances are capable of giving oxygen to 
others. A substance capable of thus giving up its oxygen is 
called an oxidizing agent. A body taking the oxygen is called 
a deoxidizing or reducing agent. Chlorine may act as an oxidiz- 
ing agent in the presence of moisture by uniting with hydrogen 
and liberating the oxygen with which it was combined. 

Oxygen is the constituent of the atmosphere which actively 
supports the respiration of animals ; but it occurs here diluted 
with four-fifths of its volume of nitrogen, being too active when 
in the pure state. An animal placed in an atmosphere of pure 
oxygen shows great stimulation of all the vital functions for 
a time, but it soon expires from overstimulation and exhaustion, 
due to the rapid oxidation of its tissues. Oxygen is used in 
medicine by inhalation in those diseases which reduce the sur- 
face of absorption of oxygen from the air, such as tuberculosis 
and pneumonia; it is used also for the temporary sustenta- 
tion of life in some cases of impending dissolution. 

Experiment. Place a small quantity of a mixture of equal parts of 
potassium chlorate and black oxide of manganese in a large test-tube, 
fit the delivery tube and heat carefully. Collect the escaping oxygen 



96 TEXT-BOOK OF CHEMISTRY 

over water and observe its properties. Oxygen is not combustible but 
it is a supporter of combustion. Mix a small test-tubeful with two 
small test-tubefuls of hydrogen in a large test-tube. When the mixture 
is ignited explosion takes place with formation of water. Complete 
the equation : 

2KCIO3 + heat = 

How many grammes of oxygen can be obtained from 10 grammes 
of KCIO3? How many liters? 

Ozone. 

Formula, O g . Molecular Weight, 48. 

Ozone is an allotropic modification of oxygen. It was dis- 
covered in 1840 by Schonbein. 

Preparation. Ozone can be obtained by the passage of non- 
luminous electrical discharges through oxygen or air; also by 
oxidation of phosphorus partly covered with water. 

Properties. Ozone is a gaseous body, having slightly 
bluish tinge when viewed in large quantity, the odor of fresh 
eggs and a density one-third greater than that of oxygen. It 
can be liquefied by pressure, and when heated to about 237 is 
converted into oxygen. 

On account of its density ozone is said to have three atoms 
to the molecule, instead of two as found in ordinary oxygen. 
It is more active as an oxidizing agent than oxygen, and in the 
act of oxidation one atom combines with the body attacked, 
while the other two atoms are given off as ordinary oxygen. 
Ozone decomposes iodide of potassium with liberation of iodine, 
and may be recognized by moist strips of paper saturated with 
potassium iodide and mucilage of starch, giving a blue color. 

COMPOUNDS OF OXYGEN WITH HYDROGEN. 

These elements unite in two proportions : Hydrogen mon- 
oxide, or water, H 2 ; and hydrogen dioxide, or peroxide, 
H 2 2 . 



THE NON-METALLIC ELEMENTS 97 

WATER. 

Formula, H 2 0. Molecular Weight, 18. 

Water, as found in nature, is never in an absolutely pure 
condition. It contains impurities derived from the atmosphere 
and impurities derived from the soil. 

Impurities commonly found in water and derived from air 
are the gases, oxygen, nitrogen, and carbon dioxide, also traces 
of nitrate and sulphate of ammonium. Impurities derived from 
the soil are sodium chloride; chlorides, carbonates, and sul- 
phates of calcium, magnesium and potassium. Hard water 
contains comparatively large quantities of these salts, especially 
the carbonates and sulphates of calcium. Temporary hardness 
is that which is due to the presence of calcium carbonate held 
in solution by carbonic acid gas. When the water is boiled 
temporary hardness disappears because the carbonic acid gas is 
expelled and the calcium carbonate is precipitated. Permanent 
hardness is due to salts dissolved in the water, chief of which 
are calcium sulphate and chloride; these do not precipitate 
upon boiling. 

Mineral waters contain a sufficient quantity of salts to im- 
part a decided taste or to impart medicinal properties. The 
chief varieties of mineral waters are designated in the following 
terms : Bitter waters contain the sulphate and chloride of mag- 
nesium. Chalybeate waters contain iron carbonate or sulphate. 
Sulphur waters contain hydrogen sulphide and sulphides of cal- 
cium, magnesium and potassium. Effervescent waters contain 
carbon dioxide. Alum waters contain the sulphate of aluminum 
and potassium. Lithia waters contain the salts of lithium, usu- 
ally the carbonate. 

In order to obtain water in a state of purity it has to be sub- 
jected to distillation. The first and last portions are rejected, 
in distilling water for its purification, in order to insure the 
absence of foreign matter. 



98 TEXT-BOOK OF CHEMISTRY 

Drinking water should not be chemically pure, but should 
contain from 3 to 5 parts of dissolved mineral matter in 10,000 
parts of water and a small percentage of carbonic acid gas, 
about one per cent, by volume. The presence of this small 
percentage of dissolved mineral and gas gives palatability and 
lightness to the water, which would have a " flat," insipid taste 
if it were chemically pure. The presence of organic matter in 
drinking water renders it unwholesome and dangerous to health. 

Properties. Water is odorless, tasteless, blue in deep layers, 
can be volatilized by heat and solidified by cold. Temperature 
of greatest density of water is 4 C. The solvent power of 
water is very great, it being more largely used as a solvent than 
any other liquid. Its solvent power is increased by heat except 
in the case of a few salts, such as sodium chloride and some of 
the salts of calcium. 

Water is a neutral body, but it combines with some oxides 
to form acids, and with some other oxides to form bases. A 
hydroxide, formerly called a hydrate, contains the radical OH. 
A hydrous body is one which contains water. An anhydrous 
body is one which does not contain water. An anhydride is a 
body which by union with water forms an acid. 

The crystalline character of many salts is due to the pres- 
ence in a solid state of a certain number of molecules of water. 
This water is referred to as the water of crystallization, and 
when it is driven off by heat the crystal falls to powder. 

A salt, when it loses water of crystallization by exposure to 
air is said to undergo efflorescence. Some other salts when ex- 
posed to air absorb moisture and are partly or completely lique- 
fied ; this property is known as deliquescence. The term hygro- 
scopism means power to absorb moisture from the air, and it is 
usually applied in speaking of liquid or organic substances. 



THE NON-METALLIC ELEMENTS 99 

Hydrogen Peroxide. 

Formula, H 2 2 . Molecular Weight, 34. 
Preparation. Prepared by acting upon barium dioxide with 
an acid, and carefully evaporating the product in a vacuum 
at a low temperature. The following equation shows the action 
of sulphuric acid upon barium dioxide : 

Ba0 2 + H.SO* = BaS0 4 + H 2 2 . 

Barium dioxide Sulphuric acid Barium sulphate Hydrogen peroxide 

Hydrogen peroxide may also be obtained by action of carbon 
dioxide and water upon barium dioxide, as shown in the fol- 
lowing : 

C0 2 + H 2 + Ba0 2 = BaCOs + H 2 2 . 

Carbon dioxide Water Barium dioxide Barium carbonate Hydrogen peroxide 

The insoluble barium sulphate or carbonate, as the case may 
be, is separated by filtration, and the filtered liquid evaporated 
in a vacuum. 

A solution of hydrogen peroxide can be prepared, for use in 
cases in which the presence of a sodium salt does not interfere, 
by adding an acid to sodium dioxide, Na 2 2 , and water. 

Properties. Pure hydrogen dioxide is a colorless, odorless, 
corrosive, oily liquid; specific gravity 1.45; freely soluble in 
water, glycerine or ether. It bleaches organic coloring matter, 
and easily decomposes into oxygen and water. 

The commercial liquid, so largely used in medicine as an 
antiseptic, is a solution in water of about 3 per cent, strength, 
slightly acid in reaction, having all the properties of the per- 
oxide except that it is not oily nor corrosive. The term " vol- 
ume solution " refers to the number of volumes of oxygen that 
can be obtained from one volume of the commercial liquid. A 
ten volume solution is 3 per cent, by weight of H 2 2 . 

Tests. 1. Strips of paper saturated with solution of potas- 
sium iodide and mucilage of starch give a blue color with hydro- 
FC, 



100 TEXT-BOOK OF CHEMISTRY 

gen dioxide, due to the fact that the dioxide liberates iodine 
which turns blue when in contact with starch. 

2. Peroxide of hydrogen is decomposed by silver oxide with 
liberation of oxygen, according to the equation: 



A g2 


+ H 2 2 = 


Ag 2 


+ 


2 


+ 


H 2 0. 


Silver oxide 


Hydrogen peroxide 


Silver 




Oxygen 




Water 



3. Acidified solution of potassium permanganate is decolor- 
ized by peroxide of hydrogen with evolution of oxygen. 

4. Potassium dichromate added to peroxide of hydrogen 
which has been acidified with sulphuric acid gives a blue color, 
and the mixture when shaken with ether separates into two 
layers ; blue perchromic acid formed in the reaction dissolves in 
the ether. 

NITROGEN (Azote). 
Symbol, N. Atomic Weight, 14. 
Quantivalence, III and V. 
Occurrence in Nature. Nitrogen is found in the free state 
in abundance in the atmosphere, of which it constitutes four- 
fifths. Compounds of nitrogen are found in animal tissues, 
in plants, in ammonia, in nitrates, nitrites and hyponitrites. 

Preparation. By heating ammonium nitrite, according to 
the equation : 

N£LN0 2 = 2H 2 + N 2 . 

Ammonium nitrite Water Nitrogen 

Prepared in an impure state by burning phosphorus in a 
confined portion of air over water whereby the oxygen is 
exhausted, leaving nitrogen. 

Properties. A colorless, odorless, tasteless gas, fourteen 
times heavier than hydrogen. At a temperature of — 146 and 
pressure of 33 atmospheres it is a colorless liquid, which boils 
at — 1 94 at pressure of atmosphere. Nitrogen is not com- 
bustible nor a supporter of combustion, and is characterized 



THE NON-METALLIC ELEMENTS 



IOI 



Fig. 29. 



by its inertness, or lack of affinity for other elements. It can 
be made to unite with other elements, however, by indirect 
means, but many of its compounds are prone to decompose, 
and some do so with ex- 
plosive violence. The pres- 
ence of nitrogen in the at- 
mosphere serves to dilute 
the oxygen, and thus ren- 
der it fit for respiration. 




Preparation of Nitrogen. 



Experiment. Place a piece 
of phosphorus upon cork float- 
ing in water. (Phosphorus 
must be cut under water and 
not held in the fingers, since 
the warmth of the hand is suf- 
ficient to cause it to ignite.) 
Ignite the phosphorus by touching it with a heated glass rod. As the 
phosphorus burns, invert a beaker over the cork. The burning phos- 
phorus removes oxygen, and when the white fumes of phosphoric ox- 
ide have been absorbed by the water nitrogen remains. Examine its 
properties. Notice that it is neither combustible nor a supporter of 
combustion. 

The Atmosphere consists chiefly of a mechanical mixture of 
nitrogen and oxygen, about four-fifths of the former and one- 
fifth of the latter, as follows : 



Nitrogen, 76 
Oxygen 



parts by wt, or 79.22 parts by volume. 



2 3-Oi , , 20.78 . , . 

parts by wt., or parts by volume. 

100.00 100.00 



Besides nitrogen and oxygen the air contains watery vapor, 
carbon dioxide, traces of ammonium nitrate, hydrogen peroxide, 
ozone and solid suspended particles of dust. 

Argon. Discovered in the atmosphere by Lord Rayleigh and Pro- 
fessor Ramsey in 1894. Air contains about one per cent, of this ele- 
ment. It is a colorless gas and has been liquefied. Chemically, it is 
very inert, having little or no affinity for other bodies. Symbol, A. 
Atomic weight, 40. 



102 TEXT-BOOK OF CHEMISTRY 

Krypton, neon and xenon are elements similar to argon which have 
been recently discovered in the atmosphere, but they are of so little 
importance that their names only will be mentioned. 

Helium. First discovered in the solar spectrum. Occurs in many 
minerals, in the gases given off from some springs, and in the air. 
Discovered in 1895 by Professor Ramsey. Properties like argon. 
Atomic weight, 4. Symbol, He. 

COMPOUNDS OF NITROGEN WITH HYDROGEN. 

AMMONIA. 

Formula, NH 3 . Molecular Weight, 17. 

Occurrence in Nature. Ammonia is formed in nature by 
the decomposition of nitrogenous organic matter, and from 
this source escapes into the atmosphere. It occurs in small 
amounts in combination with acid radicals in the form of 
ammonium compounds. 

Preparation. By destructive distillation of nitrogenous 
organic matter and passing the gaseous product into water 
which dissolves the ammonia. In the manufacture of coal gas 
by destructive distillation of coal, large quantities of ammonia 
are formed, and by passing the gaseous product of this dis- 
tillation through water the ammonia is dissolved out. Such 
water is known as the " ammoniacal liquor of the gas works," 
and is the chief source from which ammonia and its com- 
pounds are obtained. 

Ammonia can be liberated from ammonium compounds by 
the action of a strong alkali, as indicated in the following equa- 
tion : 

NH 4 C1 + NaOH = NaCl + H 2 + NH 3 . 

Ammonium chloride Sodium hydroxide Sodium chloride Water Amm onia 

Ammonia gas must be collected over mercury instead of 
water on account of its great affinity for the latter substance. 

Properties. Colorless gas, suffocating odor, alkaline taste 
and reaction. Ammonia is easily converted into a liquid by a 



THE NON-METALLIC ELEMENTS 



I03 



pressure of 6.5 atmospheres at io°, or by simply reducing the 
temperature to — 40 . It has great affinity for water and 
dissolves in this liquid with such energy as to cause con- 
siderable elevation of temperature: 730 volumes of the gas 




Preparation of Ammonia. 

dissolve in one of water at 15 . Ammonia is not combustible 
nor a supporter of combustion ; when inhaled it acts as a 
caustic irritant to the air passages. 

A mixture of oxygen and ammonia is explosive. Chlorine 
will burn in ammonia gas. Ammonia is a strongly basic sub- 
stance, as shown by its action upon litmus paper, its strongly 
alkaline taste and its power to combine with acids to form 
salts. The manner in which ammonia combines with acids 
is peculiar in the fact that the hydrogen of the acid is retained, 
with the formation of an ammonium compound, as shown by 
the following equation : 



NH 3 

Ammonia 



+ HC1 = NHX1. 

Hydrochloric acid Ammonium chloride 



104 TEXT-BOOK OF CHEMISTRY 

When ammonia is dissolved in water a compound is formed 
having the formula NH 4 OH, known as ammonium hydroxide, 
or hydrate, and having properties similar to those of the gas. 
A solution of this character, having 10 per cent, by weight of 
ammonia and a specific gravity of .958, is official in Aqua 
Ammonia (Spirit of Hartshorn). Stronger Water of Am- 
monia, also official, contains 28 per cent. ; specific gravity, '.897. 

For ammonia tests, see ammonium. 

Experiment. Place a little ammonium chloride in a dry small test- 
tube and add a few drops of sodium or potassium hydroxide and warm. 
Ammonia gas is given off. Complete the equation : 

NEUC1 + NaOH = 

Observe the odor of ammonia, its action on a piece of moist red lit- 
mus paper held over the open end of the tube, and observe the dense 
white fumes produced when a glass rod moistened with hydrochloric 
acid is brought over the end of the tube. 

Hydrazine, Diamine, N 2 H 4 . A compound obtained from ammonium 
sulphocyanate, of interest because it forms some important organic 
derivatives. It is a colorless, pungent gas, easily liquefied and solidi- 
fied. In chemical properties it resembles ammonia, forming a hydrate 
of the composition N 2 H 4 H 2 0. Its graphic formula is represented thus : 

H \ / H 

\N— N< 



COMPOUNDS OF NITROGEN WITH OXYGEN. 

Nitrogen forms five oxides and three acids, as follows : 
Nitrogen monoxide, N 2 — Hyponitrous acid, HNO. 
Nitrogen dioxide, N 2 2 , or NO. 
Nitrogen trioxide, N 2 O s — Nitrous acid, HN0 2 . 
Nitrogen tetroxide, N 2 4 , or N0 2 . 
Nitrogen pentoxide, N 2 O s — Nitric acid, HN0 3 . 



THE NON-METALLIC ELEMENTS 105 

Nitrogen Monoxide. 
Formula, N 2 0. Molecular Weight, 44. 

Synonyms. Nitrous oxide, laughing gas. 

Nitrogen monoxide was discovered by Priestley in 1776; its 
anaesthetic properties were discovered by Sir Humphrey Davy 
in 1800; and it was first used as an anaesthetic in dentistry by 
Doctor Wells, of Hartford, Connecticut, in 1844. 

Preparation. The gas is prepared by heating ammonium 

nitrate to a temperature of 250 , as shown in the following 

equation : 

NH4NO3 = N 2 + 2H 2 0. 

Ammonium nitrate Nitrogen monoxide Water 

Properties. A colorless, odorless gas, of sweetish taste, 
easily liquefied by a pressure of 30 atmospheres at o°, or by 
50 atmospheres at the ordinary temperature, and the liquid 
boils at — 8o°. Nitrous oxide supports combustion almost as 
actively as oxygen, and when inhaled produces exhilaration and 
insensibility. It is largely used as an anaesthetic in dentistry. 
When nitrous oxide is to be used as an anaesthetic it should be 
caused to pass through a solution of caustic potash and fer- 
rous sulphate in order to remove impurities. The pure com- 
pound can usually be obtained from the manufacturer in the 
liquid state in cast-iron cylinders. 

Experiment. Place in a dry, large test-tube a small quantity of am- 
monium nitrate, apply heat cautiously and collect the gas over water. 
Observe that it is a colorless gas, of sweetish taste and supports com- 
bustion. It is used for anaesthesia in dentistry. Complete the equation : 

NH 4 N0 3 + heat = 

Nitrogen Dioxide is a colorless gas, given off when nitric 
acid acts on metals. It takes up oxygen immediately on coming 
in contact with the air and is converted into nitrogen tetroxide, 
which is a reddish brown poisonous gas at the ordinary tem- 
perature. 



106 TEXT-BOOK OF CHEMISTRY 

Nitrogen Trioxide, or nitrous anhydride, is a dark-blue liquid 
at a temperature of — 20°. When the temperature is raised 
above this point it decomposes into NO and N0 2 . 

Experiment. Place a few fragments of metallic copper on the bot- 
tom of a test-tube and add a few drops of nitric acid. Nitrogen dioxide 
escapes as a colorless gas, and combining with more oxygen from the 
air, forms nitrogen tetroxide (N 2 4 ), a gas of deep red color, which 
is poisonous. 

Nitrogen Pentoxide, nitric anhydride, N 2 5 , is produced by 
the action of phosphoric oxide on nitric acid, as shown in the 
equation : 

2HNO3 + P 2 5 = N 2 5 + 2HPO3. 

Nitric acid Phosphoric oxide Nitrogen pentoxide Metaphosphoric acid 

Nitric anhydride forms colorless crystals, which are very 
unstable, and sometimes undergo decomposition with explosive 
violence. It has powerful affinity for water, with which it 
combines to form nitric acid, HNO s . 

The first, third and fifth of the above oxides have their 
corresponding acids, produced theoretically by adding a mole- 
cule of water to each. 

Hyponitrous acid, HNO, is a very unstable white solid, 
which decomposes into the oxide and water. It forms com- 
pounds called hyponitrites. 

Nitrous acid, HN0 2 , is not known in the pure state but ex- 
ists in solution and in its salts, the nitrites. These two acids, 
hyponitrous and nitrous, are formed in nature by the oxidation 
of ammonia, and their presence in drinking water indicates 
previous contamination with nitrogenous organic matter. 

Nitric Acid. 
Formula, HNO s . Molecular Weight, 63. 
Synonyms. Hydric nitrate, aqua fortis. 
First prepared in the eighth century by distilling saltpeter 
with alum. 



THE NON-METALLIC ELEMENTS 



I07 



Nitric acid is formed in nature by oxidation of the product 
of decomposition of nitrogenous organic matter, and is found 
as nitrates in some soils in Chili and India. The formation of 
deposits of nitrates in the soil is due to the decomposition 
of nitrogenous organic matter into ammonia, which in turn is 
oxidized into nitric acid ; the acid, by union with bases present, 
forms nitrates. Nitric acid is formed in traces in the atmos- 
phere by electrical discharges. 

Preparation. Nitric acid is prepared by distilling a mixture 
of sodium nitrate and sulphuric acid, according to the following 
equation : 



2NaN0 3 

Sodium nitrate 



+ H 2 S0 4 = 

Sulphuric acid 



2HNO3 
Nitric acid 



+ Na 2 SO,. 

Sodium sulphate 



Fig. 31. 




Preparation of Nitric Acid. 



108 TEXT-BOOK OF CHEMISTRY 

Properties. When pure, a colorless, fuming, corrosive 
liquid, which turns brown by exposure to light because of the 
formation of nitrogen tetroxide, oxygen and water. The acid 
has a powerful affinity for water, but it may be obtained in the 
anhydrous state by distilling from strong sulphuric acid. 

The ordinary official acid contains 68 per cent, of absolute 
acid and has a specific gravity of 1.403. The acid is completely 
volatilized by heat; it stains organic matter yellow; it is a 
powerful oxidizing agent. Nitric acid combines with bases to 
form nitrates, all of which are soluble. The diluted acid con- 
tains 10 per cent, by weight of pure HNO s , and has a specific 
gravity of 1.054. 

Poisonous Properties. Nitric acid, taken undiluted, acts as a 
powerful corrosive irritant poison, producing a yellow discolora- 
tion of the tissues. The antidote in case of poisoning is sodium 
carbonate, lime water, or other weak alkali, and demulcent 
drinks. The stomach pump should not be used, since there is 
danger of perforating the corroded wall of the stomach. 

Tests for Nitric Acid and Nitrates. 

1. Nitrates heated with sulphuric acid and copper filings, or 
nitric acid heated with copper filings, give off fumes of nitrogen 
dioxide, which become reddish brown in contact with air. 

2. Solution of indigo is changed to yellow by nitric acid, or 
by nitrates to which sulphuric acid has been added. 

3. Nitrates deflagrate when heated on charcoal. 

4. To solution of a nitrate add ferrous sulphate; when sul- 
phuric acid is poured down the side of the test-tube a brown 
color is produced at the line of contact of the two liquids. 

5. Pyrogallic acid added to the solution of a nitrate, and sul- 
phuric acid poured down the side of the test-tube produces a 
deep brown coloration at the line of contact of the two liquids. 

6. Add solution of diphenylamine in strong sulphuric acid 



THE NON-METALLIC ELEMENTS ICX) 

to solution of a nitrate, and pour sulphuric acid down the side 
of the test-tube, a deep blue color is formed at the line of con- 
tact of the liquids. 

Detection of Impurities. Evaporate some of the acid in a glass ves- 
sel ; it should be completely volatilized without residue, showing ab- 
sence of mineral impurities. Hydrochloric acid may be detected by 
silver nitrate ; sulphuric acid by barium chloride. Test for iodine by 
diluting with water and adding mucilage of starch. 

CARBON. 

Symbol, C. Atomic Weight, 12. Quantivalence, IV. 

Occurrence in Nature. Carbon is found in abundance in 
the free state in the form of graphite or plumbago, turf and coal, 
and in smaller quantity in the diamond. It occurs in the form 
of combination in all organic bodies, in carbon dioxide and in 
the form of carbonates in many minerals, such as marble, dolo- 
mite, limestone, etc. 

Properties. Carbon occurs in three allotropic modifications 
which differ greatly in properties. Diamond is a beautiful, 
transparent, crystalline solid, consisting of pure carbon. It is 
the hardest substance known, and is converted into carbon 
dioxide by heating in an atmosphere of oxygen. Graphite, 
plumbago, or black lead is a dark-gray mineral, having a slight 
metallic lustre. It is used for making lead pencils, crucibles, 
as a lubricant and as stove polish. Amorphous carbon, a 
black solid, is found as coal, as lampblack and the various kinds 
of charcoal. 

Carbon is a solid, infusible, insoluble body ; permanent in the 
air. When heated to the high temperature of the electric fur- 
nace it softens and volatilizes to a very slight extent. 

Carbon has little affinity for other elements, but at a high 
temperature it combines with some of the metals to form car- 
bides, and by indirect means it can be made to unite with many 
of the non-metals. When heated in air or oxygen it burns, 



no 



TEXT-BOOK OF CHEMISTRY 



forming carbon dioxide; and at elevated temperatures it is 
capable of removing oxygen from other bodies, thus acting 
as a powerful reducing agent. 



COMPOUNDS OF CARBON WITH HYDROGEN. 

These compounds are exceedingly numerous, and form de- 
rivatives with most of the other elements. They were for- 
merly thought to be produced only in the bodies of plants 
and animals, and their classification into Organic Compounds 

is still retained. Organic 
22 ' compounds will be studied 

subsequently, but the fol- 
lowing are of interest at 
present : 

Methane, Marsh Gas, 
CH 4 ; Ethene, Olefiant Gas, 
C 2 H 4 ; and Acetylene, C 2 H 2 , 
are produced in the de- 
structive distillation of coal, 
and are present in illu- 
minating gas along with 
hydrogen (H) and carbon 
monoxide ( CO ) . They are 
colorless, combustible gases. 
Flame is a jet of the 
above gases undergoing the 
act of combustion. In the 
case of a solid the heat 
of combustion produces the 
gases, which undergo rapid oxidation. The flame consists 
of three cones: an inner or central cone containing unburnt 
gases, because the oxygen is unable to reach that part ; a sec- 
ond, or middle cone, enveloping the former, in which the gases 




Structure of Flame. 



THE NON-METALLIC ELEMENTS 



III 



are partially burnt and burning, this cone contains particles of 
free carbon, because the hydrogen of the burning gases appro- 
priates most of the available oxygen, and the carbon particles 

being heated to a high tem- 
perature are very luminous; 

Fig. 34. 



Fig. 33. 




Action of Wire Gauze on Flame. 

a third, or outer cone, envelop- 
ing the others, in which the 
gases undergo complete oxida- 
tion, giving off the largest 
amount of heat and almost no 
light. The oxidizing flame is 
the non-luminous part; the de- 
oxidizing, or reducing flames, 
is the luminous part. 

Temperature of Ignition is 
the point of temperature at 
which a substance will take fire 
in air or oxygen. This tem- 
perature varies with different 
bodies, and in combustible sub- 
stances it is maintained by the 
burning body. The vapor of 
carbon bisulphide is set on fire 
by a heated glass rod at a tern- 




Sir Humphrey Davy's Safety 
Lamp. (Sectional View.) 



112 TEXT-BOOK OF CHEMISTRY 

perature of about 149 , while ordinary coal-gas does not take 
fire when brought in contact with a red-hot iron rod. Slow 
oxidation of course takes place at much lower temperatures. 

If a mixture of coal-gas and air be passed through an iron 
tube, and ignited, it will burn at the extremity of the tube, 
because the conductivity of the metal keeps the temperature of 
the gases inside the tube below the igniting point. This prin- 
ciple is illustrated in the Bunsen burner, which Consists of a 
metal tube, through which gas is permitted to flow, with open- 
ings for air near the bottom. By means of this arrangement 
complete oxidation takes place throughout the flame, producing 
a high degree of heat and no light. 

Davy's Safety Lamp. The principle of the safety lamp is 
shown by holding a piece of wire gauze, having about 700 
meshes to the square inch, over a jet of gas. The gas when 
ignited above the gauze will burn there without taking fire 
underneath; each mesh of the gauze acts as a fine metal tube 
and reduces the temperature of the gas below the point of 
ignition so that the flame cannot pass through. 

The Davy safety lamp consists of an oil lamp, having an 
ordinary flame, surrounded by a covering of fine wire gauze. 
If this lamp be placed in a combustible gas, the flame cannot 
pass to the outside of the gauze, though the gas may burn on 
the inside. 

COMPOUNDS OF CARBON WITH OXYGEN. 
Carbon Monoxide, Carbonic Oxide. 
Formula, CO. Molecular Weight, 28. 
Carbon monoxide is produced by incomplete combustion of 
carbon, or by the passage of carbon dioxide (C0 2 ) over red- 
hot charcoal (C). The action of carbon dioxide on red-hot 
charcoal is shown in the equation : 

C0 2 + C = 2CO. 

Carbon dioxide Carbon Carbon monoxide 



THE NON-METALLIC ELEMENTS I I 3 

It is also formed by conducting watery vapor over red-hot 
charcoal, thus : 

H 2 + C = CO + H 2 . 

Water Carbon Carbon monoxide Hydrogen 

The gas formed in this way is known as water-gas ; it is used 
as such for heating purposes, and when mixed with hydro- 
carbons it is largely employed for illumination. 

Properties. Carbon monoxide is a colorless, almost odorless, 
tasteless gas. It is highly combustible, burning with a pale 
blue flame, forming carbon dioxide. The gas when inhaled 
acts as a poison by forming a compound with the hemoglobin 
of the blood which prevents the absorption of oxygen. 

Conditions favoring the formation of carbon monoxide are 
present in fireplaces and stoves ; in these, the coal is oxidized in 
the lower part of the grate into carbon dioxide, and this gas in 
passing upward over red-hot coals is reduced to carbon monox- 
ide. At the surface of the grate, carbon monoxide comes in 
contact with the air and burns with a pale blue flame. On 
account of the formation of this gas under these conditions, 
cases of poisoning have occurred in close rooms with imperfect 
draft and ventilation. 

Formic Acid, H 2 C0 2 , which would result theoretically from the union 
of carbon monoxide with water, thus : 

CO + H 2 = H 2 C0 2 , 

is an organic acid and is not produced in this manner. It is formed 
by oxidation of methyl alcohol, and will be studied in the section on 
organic chemistry. 

Carbon Dioxide (Carbonic Acid), Carbonic Acid Anhydride. 
Formula, C0 2 . Molecular Weight, 44. 
Occurrence in Nature. Carbon dioxide is constantly being 
formed in nature by the combustion of carbon or its compounds, 
and by the respiration of animals. It is found in the air, in 
water and in the soil. 
9 



114 TEXT-BOOK OF CHEMISTRY 

The constant formation of this gas would probably result in 
its accumulation in the air if it were not being used up in the 
economy of nature. It is absorbed by members of the vege- 
table kingdom through their leaves and other green parts in 
plant respiration, the plant giving out oxygen in exchange, 
which serves to sustain animal life. Carbon dioxide is also 
taken up in the mineral kingdom in the disintegration of cer- 
tain soils, forming carbonates. 

Preparation. This compound is easily obtained by the 
action of acids upon carbonates, and collecting over water. 
The action of sulphuric acid upon calcium carbonate is a con- 
venient method, as shown in the equation : 

CaC0 3 + H 2 S0 4 = CaS0 4 + H 2 + C0 2 . 

Calcium carbonate Sulphuric acid Calcium sulphate Water Carbon dioxide 

Properties. A colorless gas; pungent odor and taste; acts 
as a poison when inhaled by exclusion of oxygen and inter- 
fering with exchange of gases in the lungs. Its density as com- 
pared with hydrogen is 22. ■ The gas can be reduced to a liquid 
by a pressure of 38 atmospheres at o°, and to a white solid by 
rapid evaporation of this liquid. It is not combustible nor a 
supporter of combustion, but it has the power to extinguish 
flame. 

Carbon dioxide is soluble in an equal volume of water at 
the ordinary temperature and pressure of the air, and its 
solubility is greatly increased by increase of pressure. Ordi- 
nary " soda water " is a solution of the gas in water under 
pressure. 

A solution of carbon dioxide in water forms carbonic acid, 
according to the equation : 

C0 2 + H 2 = H 2 C0 3 . 

Carbon dioxide Water Carbonic acid 

Carbonic Acid, H 2 C0 3 , has never been separated in a pure 
state, but decomposes into water and carbon dioxide when this 



THE NON-METALLIC ELEMENTS I I 5 

is attempted. It is presumed to be present in solution in water, 
imparting feebly acid properties to the liquid. It is a weak 
dibasic acid, whose hydrogen can be replaced by most metals, 
forming carbonates. 

Tests for Carbonates. 
i . A strong acid added to a carbonate produces effervescence, 
due to escape of carbon dioxide (C0 2 ). 

2. The carbon dioxide liberated in the above test produces 
a turbidity, or milkiness, when passed through lime water, due 
to precipitation of calcium carbonate. 

3. Solutions of carbonates or carbon dioxide precipitate most 
of the heavy metals in the form of carbonates. 

SILICON. 

Symbol, Si. Atomic Weight, 28. Quantivalence, IV. 

Occurrence in Nature. Found very widely distributed in 
nature in all soils in the form of silicon dioxide, Si0 2 , in sand, 
rock crystal, quartz and agate. Found as silicates, in which 
silicic acid has entered into combination with metals, in soils and 
rocks. Found also in the stalks of certain plants. 

Preparation. By heating silicon fluoride with metallic 
sodium. 

Properties and Uses. Silicon shows much similarity in 
properties to carbon, existing in three allotropic modifications. 
It burns when heated in air, forming silicon dioxide, Si0 2 . 
The dioxide is the only oxide known, it is an acid oxide, form- 
ing silicates with basic metallic oxides. Nearly all silicates, 
except silicates of the alkalies, are insoluble in water and acids. 

Sodium silicate (soluble glass) is employed for making casts 
in the treatment of fractures of bones of the extremities. A 
thick solution of the salt is rubbed into each layer of bandage 
as the latter is applied. This dressing forms a rigid casing for 
the limb as soon as its moisture has evaporated. 



Il6 TEXT-BOOK OF CHEMISTRY 

Test for Silicates. 
Silicates may be recognized by fusing them with a mixture 
of the carbonates of sodium and potassium, dissolving this 
soluble glass in water and adding hydrochloric acid, which pre- 
cipitates the silicon as a gelatinous powder of hydroxide. By 
evaporation of the above mixture completely to dryness on the 
water bath, and treating the dry residue with water acidulated 
with hydrochloric acid, the silicon is completely separated, re- 
maining as a white powder of silicon dioxide. 

BORON. 

Symbol, B. Atomic Weight, n. Quantivalence, III. 

Occurrence in Nature. Boron is not found in nature in the 
free state but occurs in combination in the form of boric acid 
or sodium borate, dissolved in the water of inland lakes, or in 
volcanic lagoons. 

Preparation and Properties. By heating boron trioxide 
with metallic sodium, sodium borate and free boron are pro- 
duced ; when this mixture is washed with water sodium borate 
is removed, leaving boron as the residue, which must be care- 
fully dried to prevent its taking fire in the air. 

Boron is a greenish-brown amorphous powder, which takes 
fire when heated in the air forming boron trioxide, B 2 O s . It 
is acted on by the oxygen acids, oxidized by water vapor, and 
combines with nitrogen when heated. Fused alkalies and 
chlorine attack it readily, the former yielding borates. 

Boric Acid, Boracic Acid. 

Formula, H 3 B0 3 . Molecular Weight, 61.54. 

This acid occurs in nature in combination as sodium borate ; 
it occurs in the free state in the hot volcanic lagoons of 
Tuscany. 

Preparation. Prepared by evaporating- and crystallizing the 



THE NON-METALLIC ELEMENTS 1\J 

naturally occurring solution, or by treating hot solution of 
sodium borate with sulphuric or hydrochloric acid, from which 
crystals of boric acid separate on cooling. The equation shows 
the formation of boric acid from sodium tetraborate, the natur- 
ally occurring salt: 

Na 2 B40 7 .ioH 2 + 2HCI = 2NaCl + 4H3BO3 + 5H 2 0. 

Sodium tetraborate Hydrochloric acid Sodium chloride Boric acid Water 

Properties. Transparent, colorless, shining, scaly crystals ; 
soluble in about 18 parts of water, more soluble in hot; 
soluble in alcohol. On boiling the aqueous solution much of 
the acid is volatilized and lost. When boric acid is heated to 
ioo° it loses one molecule of water, and is converted into meta- 
boric acid, HB0 2 ; when further heated to about 140 , it is con- 
verted into tetra-boric acid, H 2 B 4 7 ; and when heated to red- 
ness it forms boron trioxide, B 2 O s , the only oxide of boron. 

Boric acid is a feeble acid, the normal salts of which are not 
known. Meta- and tetra-boric acids form borates. Tetraborate 
of sodium, borate of sodium, or borax, is the most important 
salt, and will be studied with the compounds of sodium. 

Tests for Boric Acid and Borates. 

1. Borate of sodium heated in the flame on a loop of plati- 
num wire forms the borax bead. 

2. Add to a borate some strong sulphuric acid and a little 
alcohol and ignite ; the flame has a greenish tinge. 

3. A solution of a calcium, barium, or silver salt added to a 
solution of a borate gives a white precipitate. 

SULPHUR. 

Symbol, S. Atomic Weight, 32. Quantivalence, II. 
Occurrence in Nature. Sulphur was well known to the 
ancients because it occurs in nature in abundance in the free 
state. It is found in the crevices of volcanic craters and in 



115 TEXT-BOOK OF CHEMISTRY 

volcanic districts. Compounds of sulphur occur in small quanti- 
ties in the bodies of animals ; they occur in abundance in the 
mineral kingdom as sulphates and sulphides of the metals. 
Sulphur occurs also as hydrogen sulphide in sulphur waters 
and in volcanic gases. 

Preparation. The element is prepared by subliming the 
crude sulphur found in nature, and further purified by wash- 
ing and drying the sublimate. 

Properties. When pure it is a pale-yellow, brittle solid; 
odorless and tasteless. Sulphur, when crystallized from a 
solution of bisulphide of carbon, forms rhombic octahedral 
crystals; the form in which it is usually seen. When melted 
and allowed to cool slowly, it forms prismatic crystals. By 
heating to a temperature of about 230 ° and pouring into water, 
a brown, plastic, amorphous variety is obtained. 

Sulphur is almost insoluble in alcohol and ether, but easily 
dissolves in bisulphide of carbon and ethereal oils. It melts 
into a yellow liquid at 115 , which becomes viscid at 250 ; when 
further heated it becomes again liquid, at about 300 , and boils 
at about 440 , giving an orange-yellow vapor. It burns when 
heated in the air (260 ) with formation of sulphur dioxide, 
but can be distilled when air is excluded. In its compounds 
sulphur shows much resemblance to oxygen, and forms sul- 
phides with most of the metals. 

Varieties of Sulphur. Sublimed sulphur, or Flowers of 
sulphur, made by subliming sulphur. A yellow, finely crystal- 
line powder. Washed sulphur, made by washing the sublimed 
variety with weak ammonia water and then with pure water. 
Precipitated sulphur, made by boiling sulphur with calcium 
hydrate and water, and precipitating the resulting solution of 
calcium sulphide and polysulphides with hydrochloric acid, 
washing and drying the precipitate. In this variety the sulphur 
is in a very pure and finely divided state. Roll-Sulphur, or 
Brimstone, made by melting sulphur and pouring it into moulds. 



THE NON-METALLIC ELEMENTS II9 

COMPOUNDS OF SULPHUR WITH HYDROGEN. 

Hydrogen Sulphide, Hydrosulphuric Acid, Sulphuretted Hydrogen. 
Formula, H 2 S. Molecular Weight, 34. 

Occurrence in Nature. This compound is found in the 
gases issuing from volcanoes, and in sulphur waters; it is 
formed during the decomposition of organic matter containing 
sulphur, contributing largely to the offensive odor of putrefac- 
tion. 

Preparation. Hydrogen sulphide is prepared by the action 
of a mineral acid upon a metallic sulphide. A convenient 
method of preparation consists in adding water and sulphuric 
acid to fragments of ferrous sulphide, the escaping gas being 
collected over water. This reaction is represented by the 
equation : 

H 2 S0 4 + FeS + *H 2 = FeSO* + H 2 S + *H 2 0. 

Sulphuric acid Ferrous sulphide Water Ferrous sulphate Hydrogen sulphide Water 

Properties. Hydrogen sulphide is a colorless gas, having 
a disagreeable and offensive odor. At the ordinary tempera- 
ture, and a pressure of 14 atmospheres, it condenses to a color- 
less liquid ; it burns in the air with a blue flame, forming water 
and sulphur dioxide ; it acts as a reducing agent on account of 
its affinity for oxygen; it is soluble in about three volumes of 
water, conferring its properties upon the latter, and forming 
a weak acid solution; its salts are called sulphides, most of 
which are insoluble. Hydrogen sulphide is a valuable reagent, 
and it is frequently used in chemical analysis. 

When inhaled, the gas acts as a powerful poison, producing 
insensibility and asphyxia. The best antidote is fresh air, and 
very dilute chlorine obtained by moistening a towel with dilute 
acetic acid and sprinkling the inside with a few grains of bleach- 
ing powder. 



120 TEXT-BOOK OF CHEMISTRY 

Tests for Hydrogen Sulphide. 

1. A solution of salts of lead, copper, silver, or mercury gives 
a black precipitate with hydrogen sulphide or soluble sulphides. 

2. By treating a solid sulphide with dilute hydrochloric or 
sulphuric acid hydrogen sulphide is given off, and may be 
recognized by its odor. Strips of paper moistened with solu- 
tion of lead acetate turn black when brought in presence of the 
gas. In order to apply the above test to ferric sulphide, the 
sulphide of mercury, platinum, or gold, zinc must be added to 
the mixture of acid and sulphide. 

Hydrogen Persulphide, H 2 S 2 , corresponds in composition to hydrogen 
dioxide, and is made in a similar way. 

It is prepared by pouring a solution of calcium persulphide into dilute 
hydrochloric acid : 

CaS 2 + 2HCI = CaCl 2 + H 2 S 2 . 

The hydrogen persulphide separates as a bad-smelling, yellow, oily 
liquid; insoluble in water, and easily decomposed into H 2 S and S. 

Bisulphide of Carbon, CS 2 , also known as carbon disulphide, is formed 
by the direct union of the two elements. It is made by passing sulphur 
vapor over red-hot charcoal, and condensing the vapors in a cool re- 
ceiver. In properties, it is a colorless, volatile, inflammable, refractive 
liquid, having a peculiar disagreeable odor. Carbon bisulphide solidi- 
fies at — n6°, and boils at 47 ; it is not soluble in water, but mixes 
with ether and alcohol; it dissolves sulphur, phosphorus, caoutchouc, 
fatty oils and resins ; it burns with a blue flame, forming carbon dioxide 
and sulphurous anhydride. 

COMPOUNDS OF SULPHUR WITH OXYGEN. 

The sulphur oxides and acids of practical interest are as fol- 
lows : 

50 2 , Sulphur Dioxide. 

50 3 , Sulphur Trioxide. 
The acids : 

SO. + H 2 = H 2 S0 3 , Sulphurous Acid. 

S0 3 + H 2 = H 2 S0 4 , Sulphuric Acid. 

H 2 S 2 7 , Pyrosulphuric Acid. 

H 2 S 2 3 , Thiosulphuric Acid. 



THE NON-METALLIC ELEMENTS 121 

Sulphur Dioxide (Sulphurous Oxide, Sulphurous Anhydride). 

Formula, S0 2 . Molecular Weight, 64. 

Sulphur dioxide occurs in nature in the gases issuing from 
volcanoes. 

Preparation. It is formed by burning sulphur in the air, 
or by the combustion of bodies containing sulphur, such as 
hydrogen sulphide or bisulphide of carbon. 

The gas is usually obtained by the action of sulphuric acid 
upon charcoal, or, in a purer state, by the action of the same 
acid upon the metals copper, mercury, or silver. It is collected 
over mercury. The equations show the action of sulphuric 
acid upon copper and upon charcoal : 

Cu + 2H 2 S0 4 = CuSO* + 2H 2 + S0 2 . 
C +2H 2 S0 4 = C0 2 +2H 2 + 2S0 2 . 

In properties sulphur dioxide is a colorless gas, with a suffo- 
cating, disagreeable odor; it condenses to a colorless liquid at 
a pressure of two atmospheres, or at — io°, and solidifies at 
— 6o°. 

The gas has the power of extinguishing flame, and acts as 
a poison when inhaled; it is a strong bleaching, disinfecting 
and deoxidizing agent; it is very soluble in water (about 43 
volumes in one of water), imparting its properties to the latter, 
and producing a solution of sulphurous acid. 

Sulphur dioxide is used as a bleaching and disinfecting 
agent : in order to be effective for these purposes the presence 
of water is necessary. 

Sulphurous Acid, H 2 SO s = 82, has not been separated 
in a pure state but occurs in solution in water or in the form of 
its salts. 

The acid is prepared by passing sulphur dioxide into water. 
The official acid is a colorless acid liquid, containing 6 per 
cent, by weight of S0 2 , and having the odor and chemical prop- 



122 TEXT-BOOK OF CHEMISTRY 

erties of the anhydride. Sulphurous acid is dibasic, and forms 
normal and bi- or acid sulphites. 

Tests for Sulphurous Acid and Sulphites. 
i. Sulphurous acid, or sulphites from which the acid has been 
liberated by the previous addition of sulphuric acid, decolorize 
an acidified solution of potassium permanganate. 

2. In the same manner, a solution of potassium bichromate 
is turned green. 

3. Barium chloride in neutral solution gives a white preci- 
pitate soluble in hydrochloric acid. 

4. Paper moistened with mercurous nitrate solution turns 
black in sulphur dioxide. 

Sulphur Trioxide (Sulphuric Anhydride). 

Formula, SO s . Molecular Weight, 80. 

This compound is prepared by passing sulphur dioxide and 
oxygen over heated platinum sponge, or by heating fuming sul- 
phuric acid and condensing the vapors. 

In properties, sulphur trioxide forms long, silky, white crys- 
tals. It fumes in the air, due to condensation of atmospheric 
moisture; it has a powerful affinity for water, with which it 
combines to form sulphuric acid. 

Sulphuric Acid, Hydrogen Sulphate (Oil of Vitriol). 

Formula, H 2 S0 4 . Molecular Weight, 98. 

This acid is more extensively used in the manufacture of 
chemical compounds and in the arts than any other one sub- 
stance, and its manufacture constitutes an important branch of 
industry. 

Sulphuric acid was discovered in the fifteenth century. It 
was first made by distilling " green vitriol," and for this reason 
and on account of its oily appearance it was called " oil of 



THE NON-METALLIC ELEMENTS I 23 

vitriol." The acid is found in nature in combination in the 

form of sulphates. 

Preparation. By passing the fumes of burning sulphur, of 

nitric acid, steam and air into large leaden chambers, the floor 

of the chamber being covered with a small quantity of water. 

These compounds act upon each other with the production of 

sulphuric acid, which falls to the floor, and is called chamber 

acid. The simplest expression of the reaction is represented 

thus: 

3 S0 2 + 2HNO3 + 2H 2 = 3HUSO4 + 2NO. 

The nitrogen dioxide takes up oxygen from the air and again 
assists in forming sulphuric acid : 

NO + O = N0 2 
S0 2 + N0 2 + H 2 = H 2 SO* + NO. 

It is seen from the above that nitric acid and the oxides of 
nitrogen, in the presence of steam, oxidize sulphurous oxide 
into sulphuric acid, and that the oxides of nitrogen act as car- 
riers of oxygen from the air. 

The chamber acid is drawn off and evaporated in leaden pans 
to expel water, until the specific gravity is about 1.72. It is 
further concentrated in glass or platinum vessels to a specific 
gravity of 1.826, containing 92.5 per cent, of acid. 

Properties. Sulphuric acid is a clear, colorless, oily liquid, 
powerfully corrosive and strongly acid in taste. Its specific 
gravity is 1.826; boiling point 338 . It has a powerful affinity 
for water, and removes the latter from the air. In combining 
with water much heat is set free, and caution must be observed 
in diluting the acid. It is a powerful acid, displacing all acids 
more volatile than itself, forming a class of compounds called 
sulphates. It is very largely used in the arts and in chemical 
operations. The acid acts on the system as a powerful corrosive 
poison. Diluted sulphuric acid contains 10 per cent, of the pure 
acid. 



124 TEXT-BOOK OF CHEMISTRY 

Antidotes. Milk of magnesia, chalk, or sodium carbonate, 
to neutralize the acid, and demulcent drinks to soothe the cor- 
roded tissues. 

Tests for Sulphuric Acid and Sulphates. 
i . Barium chloride gives a white precipitate, insoluble in 
acids. 

2. Solutions of lead salts give a white precipitate of lead 
sulphate. 

3. A solid sulphate fused on charcoal with sodium carbonate, 
by means of the blowpipe flame, and the resulting mass placed 
on a bright piece of silver and moistened with hydrochloric acid, 
gives a black stain. 

The impurities which sulphuric acid is liable to contain are lead, nitric 
acid or nitrogen trioxide, arsenic and selenium. The acid should be 
completely volatilized at 350 , without residue. The presence of lead 
is recognized by diluting with water or alcohol, when it precipitates 
white. Test for nitrates, or nitrogen oxides, by pouring a solution of 
ferrous sulphate upon some of the acid in a test-tube ; a dark color at 
the line of contact of the two liquids indicates their presence. The gas 
evolved by mixing the acid with water and pure zinc should not blacken 
a piece of paper moistened with solution of silver nitrate, showing ab- 
sence of arsenic. The presence of selenium may be discovered by dilut- 
ing the acid with water and adding sulphurous acid, when a red color 
will be formed. Organic matter imparts a dark color to the acid. 

Pyrosulphuric Acid, Fuming sulphuric acid, Nordhausen 
Oil of Vitriol, Disulphuric acid, H 2 S 2 7 . The formula for this 
acid corresponds to two molecules of sulphuric acid, from 
which one molecule of water has been withdrawn : 

2H 2 SC>4 — H 2 = H 2 S 2 7 . 

Prepared by distilling anhydrous ferrous sulphate. By dis- 
solving sulphur trioxide in strong sulphuric acid: 

H 2 S04+S0 3 = H 2 S 2 7 . 



THE NON-METALLIC ELEMENTS 125 

Properties. A thick, oily, fuming, corrosive liquid. When 
heated, sulphur trioxide is easily driven off, leaving sulphuric 
acid. 

Test. Pyrosulphates when heated give off sulphur trioxide, 
leaving the corresponding sulphate. 

Thiosulphuric Acid (Hyposulphurous Acid). H 2 S 2 3 . 
Not known in the separate state. Found in thiosulphates, 
chief of which is thiosulphate of sodium. This compound is 
made by boiling an aqueous solution of sodium sulphite with 
sulphur, and crystallizing the new compound : its official name 
is sodium hyposulphite. 

Na 2 S0 3 + S = Na 2 S 2 3 . 

Tests for Thiosulphates. 

1. Upon adding hydrochloric or sulphuric acid, sulphur 
dioxide and sulphur are liberated. 

2. Silver nitrate produces a white precipitate, which becomes 
dark on heating. 

A list of the other known acids of sulphur is given below. They 
have no interest except from a scientific standpoint, and some of them 
are found only in the form of combination in their salts. 

Hyposulphurous acid, HS0 2 . Trithionic acid, H 2 S 3 6 . 

Persulphuric acid, H 2 S 2 8 . Tetrathionic acid, H2S4O6. 

Dithionic acid, H 2 S 2 6 . Pentathionic acid, H^SsOe. 

Selenium, Se" = 79 ; and Tellurium, Te" = 126, are both rare ele- 
ments; the former usually occurs in nature in combination with sul- 
phur, the latter with metals. 

The physical properties of selenium are much like those of sulphur, 
while tellurium has the physical properties of a metal. 

Both of these elements form oxides and acids like sulphur. Selenic 
acid, H 2 Se0 4 , is distinguished for its power to dissolve gold, a property 
possessed by no other single acid. 

The hydrogen compounds of these elements have an exceedingly of- 
fensive and disgusting odor, which fixes itself with tenacity upon the 
bodies with which it comes in contact. 



126 TEXT-BOOK OF CHEMISTRY 

PHOSPHORUS. 

Symbol, P. Atomic Weight, 31. Valence, III. 

Occurrence in Nature. Phosphorus does not occur free in 
nature on account of its great affinity for oxygen. It is found 
in the form of phosphates widely distributed in all productive 
soils ; as phosphates of calcium, or apatite, iron, and aluminum. 
In some localities the phosphate of calcium is found in large 
deposits. By the disintegration of minerals containing phos- 
phorus, it is carried into the soil, from which it is absorbed by 
plants, and from these in turn by animals. In the animal sys- 
tem it is found chiefly in organic combination in the nervous 
tissues, and in the bones as tricalcium phosphate. It is elimi- 
nated chiefly by the urine. 

Brand, of Hamburg, first prepared phosphorus in the year 
1669, by igniting evaporated urine. Scheele, of Sweden, first 
succeeded in obtaining it from bones. 

Preparation. Bone-ash, or tricalcium phosphate, is digested 
with two-thirds of its weight of sulphuric acid, thus forming the 
acid, or superphosphate of calcium in solution: 

Ca 3 (P0 4 )2 + 2H2SO4 = 2CaS0 4 + CaH 4 (P0 4 )2. 

The clear solution is separated from the calcium sulphate by 

filtration, mixed with charcoal and evaporated to dryness. The 

residue, is heated to expel water and form calcium metaphos- 

phate, 

CaH4(P04) 2 = Ca(P0 3 ) 2 + 2H 2 0, 

and further heated to whiteness in retorts of clay, when phos- 
phorus and carbon monoxide are driven off, and calcium pyro- 
phosphate is formed: 

2Ca(P0 3 ) 2 + 5C = P 2 + 5CO + Ca 2 P 2 OT. 

The liberated phosphorus is condensed under water. It may 
be purified by distillation, with exclusion of air. 



THE NON-METALLIC ELEMENTS \2J 

Properties. The phosphorus obtained by distillation is a 
colorless, translucent solid, resembling white wax in appear- 
ance and consistency. By exposure to light it gradually be- 
comes opaque, and finally turns yellow, acquiring at the same 
time a coating of reddish-yellow color. At low temperatures it 
is brittle, but gradually softens under the influence of heat. At 
the temperature of the air it may be easily cut with a knife. 
When heated under water it melts at 44.4 C, and volatilizes at 
290 when air is excluded. Specific gravity, 1.83 at io°. Phos- 
phorus is insoluble in water, only slightly soluble in alcohol, 
ether, the fatty and essential oils. It is freely soluble in bi- 
sulphide of carbon and chloroform. Phosphorus unites with 
oxygen at ordinary temperatures, giving off white fumes which 
are luminous in the dark, and have the odor of garlic; when 
exposed, its temperature is soon raised to the point of ignition, 
and it takes fire spontaneously, burning with a bright, white 
light and giving off white fumes of phosphoric oxide. It has 
to be kept under water. Phosphorus takes fire at temperatures 
slightly above its melting point. On account of its inflam- 
mability great caution should be exercised in handling this 
element. Its burns are severe and difficult to heal, and it 
should only be handled under water. It combines directly with 
chlorine, bromine, iodine, sulphur ; and with many metals, form- 
ing phosphides. The quantivalence of phosphorus is three 
in some compounds and five in others. 

The molecule of phosphorus weighs 124, showing that it 
contains four atoms. 

Phosphorus forms several allotropic modifications. Amor- 
phous Phosphorus, prepared by heating phosphorus to a tem- 
perature of 260 in an atmosphere of C0 2 for 50 hours. 

This form is entirely different from the ordinary variety. It 
is a reddish-brown, amorphous powder, perfectly inert, and 
insoluble, and having little affinity for other bodies. Sp. gr. 



128 TEXT-BOOK OF CHEMISTRY 

2.14. Ordinary phosphorus is poisonous; this variety is harm- 
less. It is converted into ordinary phosphorus at 280 . 

Metallic Phosphorus is formed by heating phosphorus with 
lead in a closed tube. On cooling it separates in black, metallic, 
shining crystals. It is less active than the amorphous variety. 

Phosphorus is used in medicine in the free state in the fol- 
lowing official preparations : Phosphorated oil, containing one 
per cent.; Spirit of phosphorus, containing .12 per cent.; Pills 
of phosphorus, each containing 1/100 grain. It is also used 
in medicine in the form of its salts, which is a preferable mode 
of administration. 

Phosphorus is largely used in the manufacture of matches. 
These are usually made by dipping wooden splints in a com- 
bustible substance, such as paraffine or sulphur, and then into 
a paste of phosphorus and potassium chlorate or nitrate. 

Poisoning by Phosphorus occurs in two forms, the acute and chronk. 

Acute poisoning occurs from ingestion of the free element. The 
symptoms begin with the peculiar garlicky taste of phosphorus in the 
mouth followed by burning pain in the throat, oesophagus, and abdo- 
men. There is nausea, vomiting, often purging, dilatation of the pupils 
and great prostration. The extremities become cold, the abdomen is 
distended, and thirst is intense. In a short time the liver increases in 
size, and becomes the seat of pain and tenderness. After twenty-four 
to forty-eight hours symptoms of acute yellow atrophy of the liver 
supervene, the other symptoms having abated, and if the unfortunate 
subject survive the acute stage he generally dies of fatty degeneration 
of the internal organs. The smallest doses known to have destroyed 
life were V/2. grains in a man and J /% grain in a woman. 

The antidote for this poison is .5 to 1.0 per cent, solution of potassium 
permanganate, which should be employed in large quantities to wash 
out the stomach, and some of it should be allowed to remain in the 
stomach for absorption. 

Chronic poisoning may result from the long continued administration 
of phosphorus in large doses, or from exposure to phosphorus fumes 
such as occurs in match factories. The symptoms are great weakness, 
loss of appetite, abdominal pain, sallow complexion, necrosis of the 
lower jaw, if the teeth are carious, with swelling and suppuration of 
the gums. 



THE NON-METALLIC ELEMENTS 129 

The treatment consists in withdrawing the poison and repairing the 
teeth. 

COMPOUNDS OF PHOSPHORUS WITH HYDROGEN. 

Hydrogen Phosphide, Phosphoretted Hydrogen, Phosphine, 
PH 3 . Prepared by boiling phosphorus with solution of potas- 
sium, or sodium hydroxide, or milk of lime. Phosphine pre- 
pared in this way is spontaneously inflammable, due to the 
presence of a liquid volatile compound of the composition P 2 H 4 , 
which is highly inflammable; this compound deposits on stand- 
ing in sunlight a third phosphide of hydrogen, P 4 H 2 , which is 
a yellow solid. 

Properties. Phosphine is a colorless gas, having the odor 
of garlic. It is a powerful poison when inhaled, acting as a 
reducing agent upon the blood, and preventing further absorp- 
tion of oxygen. Hydrogen phosphide is formed during the 
decomposition of organic bodies containing phosphorus, in the 
presence of water; upon coming in contact with the air it 
takes fire spontaneously, producing the " Will o' the wisp/' or 
ignis fatuus, so often seen in marshes. 

Phosphine resembles ammonia in some of its chemical rela- 
tions, having a similar composition — NH 3 , PH 3 — but is much 
less basic. It unites with the halogen acids with retention of 
hydrogen, forming compounds like the ammonium salts : 

PH4CI — PPLBr — PHJ. 

The basic radical in these compounds is called Phosphonium. 

COMPOUNDS OF PHOSPHORUS WITH OXYGEN. 

Phosphorus forms two well-known oxides : 

P2O3, Trioxide, or Phosphorous Oxide; and 
P2O5, Pentoxide, or Phosphoric Oxide. 

Phosphorous Oxide is formed by the slow oxidation of 



130 TEXT-BOOK OF CHEMISTRY 

phosphorus in air, as a white powder, having strong affinity for 
water. By combination with water it produces phosphorous 
acid: 

P,0 3 + 3H 2 = 2H3PO3. 

Phosphoric Oxide, Phosphoric Anhydride. Prepared by 
burning phosphorus in an abundant supply of air; is a snow 
white powder. By exposure to moist air it deliquesces to a 
liquid, and, when thrown into water, combines with the latter 
with explosive violence. Its affinity for water is greater than 
that of sulphuric anhydride. Phosphoric oxide combines with 
water in three different proportions, forming three distinct phos- 
phoric acids : 

P 2 5 + H 2 =2HP0 3 , Metaphosphoric acid. 
P2O5 + 2H2O = H4P2O7, Pyrophosphoric acid. 
P2O5 + 3H 2 = 2H3PO4, Orthophosphoric acid. 

Hypophosphorous Acid, H 3 P0 2 , H,H 2 P0 2 . This acid has 
no corresponding oxide. 

Preparation. By heating the hydroxide of sodium, of 
potassium, or of calcium with water and yellow phosphorus, 
the hypophosphite of these bases is formed in solution, and 
hydrogen phosphide escapes : 

4 P + 3NaOH + 3 H 2 = 3NaH 2 P0 2 + PH 3 . 
8P + 3 Ca20H + 6H 2 = 3Ca2H 2 P0 2 + 2PH3. 

When oxalic acid is added to the solution of calcium hypo- 
phosphite, calcium oxalate precipitates, and hypophosphorous 
acid remains in solution. The acid may be separated by filtra- 
tion, and reduced to a syrupy consistence by evaporation. 

Properties. Hypophosphorous acid is a colorless, thick 
syrupy liquid, strongly acid in reaction. At a temperature 
below o°, it is a white, crystalline solid. It has strong affinity 
for oxygen and acts as a powerful reducing agent, becoming 



THE NON-METALLIC ELEMENTS I3I 

converted into phosphoric acid. It is soluble in water. A 30 
per cent, solution is official in the U. S. P. as hypophosphorous 
acid, and a 10 per cent, solution is official also as diluted hypo- 
phosphorous acid. It forms a class of salts known as hypophos- 
phites. Though containing three hydrogen atoms, it is a mono- 
basic acid, only one of these being replaceable by metals. 

Tests for Hypophosphorous Acid and Hypophosphites. 

1. When heated in the solid state they take fire, with elimina- 
tion of PH 3 , leaving the pyrophosphate. 

2. They give a white precipitate with silver nitrate which 
turns brown on heating. 

3. When mixed with a solution of mercuric chloride, and a 
few drops of HC1, a white precipitate slowly forms. 

4. They decolorize an acid solution of potassium perman- 
ganate. 

Phosphorous Acid, H 3 P0 3 , H 2 HP0 3 . 

Preparation. By dissolving phosphorus oxide in water: 

P 2 3 + 3H 2 = 2H 3 P0 3 . 

Properties. When the solution is evaporated under the re- 
ceiver of an air pump it forms crystals of pure phosphorous 
acid, which are deliquescent and very soluble in water. The 
acid is generally seen as a clear, colorless liquid, which absorbs 
oxygen and becomes converted into phosphoric acid. It is a 
powerful reducing agent. Phosphorous acid forms a class of 
compounds called phosphites. It is a dibasic acid, and forms 
normal and acid salts, according to the number of hydrogen 
atoms replaced. 

Tests for Phosphorous Acid and Phosphites. 

1. They give white precipitates with barium chloride, and 
lead acetate. Hypophosphites do not. 

2. They give a precipitate of calomel with mercuric chloride 
solution. 



132 TEXT-BOOK OF CHEMISTRY 

3. With silver nifrate a black precipitate of metallic silver. 

Phosphoric Acid, Ortho phosphoric Acid. Common or ordi- 
nary phosphoric acid, H 3 P0 4 . Occurs in nature in form of 
phosphates. 

Preparation. When phosphoric oxide is dissolved in hot 
water this acid is produced. Usually made by gently heating 
yellow phosphorus with diluted nitric acid. 

5 HN0 3 + 3P + 2H 2 = 3H3PO, + 5NO. 

The liquid is heated until fumes of nitrogen dioxide, and any 
excess of nitric acid are driven off. 

Properties. A colorless acid liquid, containing 85 per cent, 
of H 3 P0 4 , and having a specific gravity of 1.707. Phosphoric 
acid is a tribasic acid, forming salts known as phosphates, of 
which there are three classes, according to the number of hydro- 
gen atoms replaced in each case. The composition of these 
compounds is explained in the following equations : 

Na 3 P0 4 , Normal, or trisodium phosphate. 
Na 2 HP0 4 , Disodium hydrogen phosphate. 
NaH 2 P04, Sodium dihydrogen phosphate. 

Also known as primary, secondary, and tertiary phosphates 
of sodium. 

The anhydrous acid forms colorless, prismatic crystals. 

The diluted phosphoric acid of the U. S. P. contains 10 per 
cent, of the absolute acid. 

Tests for Phosphoric Acid and Phosphates. 

1. The salts of phosphoric acid give white precipitates with 
barium or calcium chloride, soluble in acetic and mineral acids. 

2. Silver nitrate gives a lemon yellow precipitate, soluble in 
nitric acid or ammonium hydroxide. 

3. With magnesium sulphate, ammonium chloride, and 
ammonium hydroxide a white precipitate forms; soluble in 
acids. 



THE NON-METALLIC ELEMENTS 133 

4. With solution of ammonium molybdate in nitric acid, a 
yellow precipitate forms ; soluble in ammonium hydroxide. 

5. Solution of egg albumen is not precipitated by. the acid 
or its salts when acidified by acetic 5cid. 

Pyrophosphoric Acid, H 4 P 2 7 . Prepared by continuously 
heating orthophosphoric acid at a. temperature of 250 . Sodium 
pyrophosphate may be easily prepared by heating the disodium 
hydrogen phosphate. 

2Na 2 HP0 4 = Na^P.Or + H 2 0. 
2H3PO4 :=HJP 2 7 +H 2 0. 

Properties. A white, crystalline solid, soluble in water, and 
when in solution gradually changes to orthophosphoric acid. 
It forms pyrophosphates, and is tetrabasic. Solutions of pyro- 
phosphates give a white precipitate with silver nitrate. 

Metaphosphoric Acid, HPO s . Prepared by heating ortho- 
phosphoric acid to a temperature of 400 °, 

2H3PO4 = 2H 2 + 2HPO3, 

also formed by dissolving phosphoric oxide in cold water, 

P 2 5 + H 2 = 2HPO3. 

Properties. A transparent, glassy mass. Sometimes called 
" glacial phosphoric acid." Deliquescent and freely soluble in 
water. It forms salts called metaphosphates, and is monobasic. 
The acid has the power of coagulating albumen, by which 
means it may be distinguished from pyrophosphoric acid. Its 
salts give a white precipitate with silver nitrate in neutral solu- 
tion, but no precipitate with magnesium sulphate, ammonium 
chloride, and hydroxide. 

THE HALOGENS. 
The elements fluorine, chlorine, bromine, and iodine, show 
great resemblance in properties ; their chemical properties being 



134 TEXT-BOOK OF CHEMISTRY 

almost identical. They are termed halogens, or salt producers, 
because they form salts by direct combination with other ele- 
ments. The compound radical, cyanogen (CN), was formerly 
classed as a member of this group. 

The halogens show a direct relation between properties and 
atomic weights, showing a gradation in properties with in- 
crease of specific gravity of the elements in the state of gas. 
Fluorine, with an atomic weight of 19, is a gas, and possesses 
the strongest chemical affinities of all known substances. 
Chlorine, whose atomic weight is 354, is a less tenuous gas, 
and its chemical affinities are not so strong as those of fluorine ; 
bromine, having an atomic weight of 79.8, is a volatile liquid, 
whose chemical affinities are less active than those of chlorine; 
and iodine, with an atomic weight of 127, is a solid and the 
least active. They are all univalent. 

CHLORINE. 

Symbol, CI. Atomic Weight, 35. Valence, I. 

Chlorine was discovered by Scheele, of Sweden, in 1774, and 
its elementary character was first established by Gay Lussac. 

Occurrence in Nature. On account of the readiness with 
which chlorine combines with other elements, it is not found 
in the free state. It is found in the form of chlorides of the 
metals, potassium, magnesium and calcium, and most abund- 
antly as the chloride of sodium in deposits in the earth, and dis- 
solved in sea water. 

Preparation. By gently heating the black oxide of manga- 
nese and hydrochloric acid in a retort chlorine is given off as 
a gas, which may be collected over warm water, or by displace- 
ment of air. 

Mn0 2 + 4HCI = 2H 2 + MnCl 2 + CI* 

It may also be prepared by the oxidizing action of potassium 
chlorate, bichromate, or permanganate, chromic or nitric acids 



THE NON-METALLIC ELEMENTS I 35 

upon hydrochloric acid, whereby the hydrogen is converted 
into water and chlorine is set free. 

By heating together manganese dioxide, sodium chloride and 
sulphuric acid according to the equation : 

MnO a - 2NaCl — 2H.S0, = MnS0 4 — Na 2 S0 4 + 2H 2 + Ch. 

Properties. A yellowish-green gas., of penetrating, suffocat- 
ing odor, producing irritation and inflammation of the air pas- 
sages when inhaled. Its specific gravity compared with hydro- 
gen is 35.45 ; with air, 2.45. At a pressure of about six atmos- 
pheres, or a temperature of 40 °, it forms a yellow liquid. One 
volume of water absorbs about two volumes of the gas at 
ordinary temperatures. When a saturated solution of chlorine 
in water is cooled below o°, yellow, scaly crystals of chlorine 
hydrate (Cl 2 10H0O) separate. 

Chemically, chlorine is a most active element. It combines 
directly with all elements except oxygen, carbon, and nitrogen, 
and it may be made to unite with these indirectly. Finely di- 
vided arsenic, antimony, or copper will take fire when thrown 
into chlorine ; phosphorus takes fire spontaneously in the gas. 
Its affinity for hydrogen is so great that it often removes this 
element from combination with other bodies. A mixture of 
hydrogen and chlorine may be kept in the dark without combi- 
nation taking place, but when such a mixture is exposed to 
diffused light, the two gradually unite; when exposed to sun- 
light, or to the influence of the electric spark, combination takes 
place with explosive violence. It decomposes hydrocarbons 
and ammonia with removal of their hydrogen. A candle burns 
in the gas with a smoky flame. Chlorine, in the presence of 
moisture, acts as a powerful bleaching and disinfecting agent, 
either by direct combination with the substance, or by uniting 
with the hydrogen of water and setting oxygen free, the liber- 
ated oxygen acting very energetically in the nascent state. It 
forms chlorides bv union with other elements. 



I36 TEXT-BOOK OF CHEMISTRY 

Experiment. Place a small quantity of black oxide of manganese in 
a dry test-tube, add enough hydrochloric acid to cover the oxide, shake 
well and heat gently. Collect the gas in a test-tube by downward dis- 
placement and cover the receiving vessel with a piece of moistened card- 
board. Observe the properties of the gas as described above. 

Chlorine Water is " an aqueous solution, containing, when 
freshly prepared, about 0.4 per cent, of chlorine, with some of 
the oxides of chlorine and potassium chloride" — U. S. P., 1900. 
It is made by placing potassium chlorate in a flask and adding 
hydrochloric acid. Cold water is then added in small por- 
tions at a time so as to dissolve the escaping gases. Chlo- 
rine water is a greenish-yellow liquid, having many of the 
properties of chlorine. By exposure to light it is gradually de- 
composed into hydrochloric acid and oxygen. 

Hydrogen Chloride, Hydrochloric Acid, Muriatic Acid, Spirit of Salt. 
Formula, HC1. Molecular Weight, 36.4. 

The elements hydrogen and chlorine enter into direct com- 
bination in the proportion of volume for volume, with the pro- 
duction of hydrochloric acid. This union takes place, when 
the two gases are mixed, under the influence of the flame, the 
electric spark or light. 

Preparation. Hydrochloric acid may be prepared by heat- 
ing a mixture of sodium chloride, or other chloride, with sul- 
phuric acid and collecting the vapors of hydrochloric acid, which 
are thereby evolved. It is also formed as a by-product in the 
manufacture of sodium carbonate by the Leblanc method : 

2NaCl + H 2 S0 4 = Na 2 S0 4 + 2HCI. 
Properties. A colorless gas, with a suffocating and pene- 
trating odor, producing great irritation to the air passages. 
The gaseous acid may be liquefied by a pressure of 40 atmos- 
pheres at a temperature of about 15 °. It is not combustible nor 
a supporter of combustion, and is very soluble in water. One 
volume of water at o° will dissolve about 500 volumes of the 
gas ; at ordinary temperatures about 400 volumes. On account 



THE NOX-METALLIC ELEMENTS I 37 

of its great affinity for water the gas forms white clouds of 
liquid hydrochloric acid in moist air. 

The hydrochloric acid of commerce and of the arts is a solu- 
tion of the above-described gas in water, and constitutes a very 
important preparation. The acid of the U. S. P. consists of 
31.9 per cent, of pure HC1 dissolved in water, and has a specific 
gravity of 1.158. It is a transparent colorless liquid, strongly 
acid in taste and reaction, and very corrosive; giving off white 
fumes when exposed to the air. 

A distinct hydrate may be formed by passing pure dry hydro- 
gen chloride into the concentrated aqueous solution, cooled to 
a temperature of — 22? . The hydrate separates in the form of 
crystals, having the formula HCI.2H0O. 

A mixture of hydrochloric acid and snow acts as a powerful 
refrigerant, reducing the temperature to — 32 °. 

The diluted hydrochloric acid of the U. S. P. contains 10 per 
cent, of pure HC1. 

Hydrochloric acid is univalent acid, forming salts known as 
chlorides. 

Tests for Hydrochloric Acid and Chlorides. 

1. A glass rod moistened with solution of ammonia brought 
in the presence of the free acid gives dense white fumes of 
ammonium chloride. 

2. Solution of mercurous nitrate when added to a chloride 
gives a white precipitate of calomel, which blackens with ammo- 
nia water. 

3. Silver nitrate added to solution of a chloride gives a white 
curdy precipitate, insoluble in nitric acid, soluble in ammonia 
water. 

4. When heated with manganese dioxide and sulphuric acid 
they give off chlorine. 

5. In strong solution they give a white precipitate with lead 
acetate, which is soluble in hot water. 



I38 TEXT-BOOK OF CHEMISTRY 

Nitro-hydrochloric Acid, Nitro -muriatic Acid {Aqua Re- 
gia) . This substance is not a definite chemical compound, but is 
made by mixing nitric and hydrochloric acids, and contains 
free chlorine, chloronitrous (NOC1) and chloronitric (NOCl 2 ) 
gases. 

By mixing 180 c.c. of nitric acid with 820 c.c. of hydro- 
chloric acid, and allowing the mixture to stand in an open vessel 
until effervescence ceases, this acid is obtained. 

Properties. A yellow, fuming, corrosive liquid ; capable of 
dissolving gold and platinum, on account of the presence of the 
free chlorine, and chloronitrous and chloronitric gases, forming 
the chlorides of these metals. 

Diluted nitro-hydrochloric acid is made by mixing 40 c.c. 
nitric acid with 182 c.c. hydrochloric acid, and, when effer- 
vescence has ceased, adding 780 c.c. of distilled water. 

THE OXIDES AND OXYGEN ACIDS OF CHLORINE. 

Though chlorine and oxygen do not enter into direct union, 
yet compounds of these elements are made by indirect means. 
The following oxides and acids are known : 

Chlorine monoxide, hypochlorous oxide, C1 2 0. 
Chlorine peroxide, or dioxide, C10 2 . 
Hypochlorous acid, HCIO. 
Chlorous acid, HCIO2. 
Chloric acid, HCIO3. 
Perchloric acid, HC10 4 . 

Hypochlorous Oxide and Acid, C1 2 and HCIO. Hypo- 
chlorous oxide is prepared by passing dry chlorine over dry 
mercuric oxide, and condensing the gas in a cooled glass tube : 

HgO + 2C1 2 = C1 2 + HgCl 2 . 

Properties. A reddish-brown liquid below 5 ; above that 
temperature a yellowish gas, which easily decomposes with ex- 
plosive violence. 



THE NON-METALLIC ELEMENTS 1 39 

Hypo chlorous acid is only known in aqueous solution, and 
can be made by passing chlorine into water containing freshly 
precipitated mercuric oxide. It may be concentrated by careful 
distillation, and has a yellow color, sweetish taste, and strong, 
bleaching properties. It is very unstable. 

This acid forms an important class of salts called hypo- 
chlorites, which are most conveniently prepared by the action 
of chlorine upon alkaline hydroxides at the ordinary tempera- 
ture of the air. 

2NaOH + Cl 2 = NaCl + H 2 + NaClO. 

Chlorous acid is of scientific interest only. 

Chloric Acid, HC10 3 , on account of its salts, is the most 
important oxygen acid of chlorine. 

Preparation. By the action of sulphuric acid upon an 
aqueous solution of barium chlorate, separating the clear liquid 
from the precipitate, and concentrating under an air-pump to a 
specific gravity of 1.28. 

Ba ( CIO3) 2 + H 2 S04 = BaSO, + 2HCIO3. 

Properties. An oily, acid liquid which decomposes at 40 . 
A powerful oxidizing agent, capable of inflaming alcohol and 
sulphur. It forms a class of salts denominated chlorates. 

Chlorates are generally prepared by the action of chlorine 
upon the hot aqueous solution of the alkalies : 

6NaOH + 3CI. = 5NaCl + 3H 2 + NaC10 3 . 

Perchloric Acid, HC10 4 . Preparation. By heating potas- 
sium chlorate, oxygen is driven of! and perchlorate of potassium 
remains. 

2KCIO3 = KC1 + KCIO4 + 2 . 

By mixing sulphuric acid with the potassium perchlorate, and 
distilling, perchloric acid is obtained : 

2KCIO4 + ILSO4 = K 2 S0 4 + 2HCIO4. 



140 TEXT-BOOK OF CHEMISTRY 

Properties. A colorless, fuming, corrosive, mobile liquid; 
specific gravity, 1.78. When kept for a few days it decom- 
poses with violent explosion. Explodes when brought in con- 
tact with organic substances. Forms perchlorates by combina- 
tion with bases. 

Tests for Chlorates. 

1. They deflagrate when heated on charcoal. 

2. They give up oxygen when strongly heated. 
Hypochlorites evolve chlorine upon the addition of an acid, 

and may be recognized by this and their bleaching properties. 

Chlorine Dioxide, Chlorine Peroxide, C10 2 , is formed by 
the action of sulphuric acid upon potassium chlorate in the 
cold. 

Properties. It is a gas, having a deep yellow color and 
powerful odor. By cold it can be condensed to a reddish-brown 
liquid. Both the liquid and gaseous chlorine dioxide are 
violently explosive. On account of the formation of this com- 
pound, sulphuric acid should not be added to potassium chlorate 

without great caution. 

BROMINE. 

Symbol, Br. Atomic Weight, 79. Valence, I. 

History and Occurrence in Nature. Discovered by Balard 
in 1826. Found in small quantities in sea water and mineral 
waters, as magnesium and sodium bromide. 

Preparation. When sea water is evaporated the sodium 
chloride first crystallizes, and the mother-liquor contains magne- 
sium and sodium bromide. The mother-liquor is treated with 
chlorine, which forms the chloride of the bases present, with 
liberation of bromine. Bromine thus liberated is separated by 
distillation and condensed in a cooled receiver : 

2NaBr + Cl 2 = 2NaCl + Br,. 
Properties. Bromine is a thin, dark, reddish-brown liquid, 
and when exposed to the air gives off yellowish-red fumes, 



THE NON-METALLIC ELEMENTS I4I 

which have a disagreeable suffocating odor and irritant action 
on the air passages. It boils at 63 and solidifies at — J° into 
a yellow-green scaly mass, having a metallic appearance re- 
sembling iodine. Its specific gravity is 2.99. It is soluble in 
thirty parts of water, and when the aqueous solution is cooled 
below 4 , crystals of bromine hydrate (Br 2 .ioH 2 0) separate. 
It is soluble in alcohol, more soluble in ether, chloroform and 
bi-sulphide of carbon. In its chemical properties bromine shows 
great resemblance to chlorine, like that element, combining 
directly with most metals, with formation of bromides. It 
differs from chlorine in the fact that its chemical affinities are 
weaker, and is displaced from its compounds by chlorine. It 
unites with hydrogen under the influence of heat, forming 
hydrobromic acid. It acts as a disinfectant and bleaching agent 
in the presence of water. 

Hydrobromic Acid, HBr. 
Preparation. By warming a solution of potassium bromide 
and dilute sulphuric acid, and separating the hydrobromic acid 
by distillation : 

2KBr + H.0SO4 + *H 2 = K 2 S0 4 + *H 2 + 2 HBr. 

If strong sulphuric acid is added to a bromide the bromine 
is set free. 

The acid may be prepared in solution by passing hydrogen 
sulphide through bromine under water until the color of bromine 
disappears : 

2H 2 S + 4H2O + ioBr — H 2 S0 4 + S + ioHBr. 

The acid is then separated by filtration and distillation. 

Properties. A colorless gas, having a pungent odor, an acid 
taste and reaction, freely soluble in water, imparting its acid 
properties to the latter. 

Diluted hydrobromic acid of the U. S. P. contains 10 per 



142 TEXT-BOOK OF CHEMISTRY 

cent. HBr, and has a specific gravity of 1.076. It is a colorless 
acid liquid. 

Hydrobromic acid by combination with bases forms bro- 
mides. 

Tests for Bromides. 

1. When a crystal of bromide is dropped in a solution of 
cupric sulphate acidified with sulphuric acid, a reddish-brown 
color is produced, due to the formation of cupric bromide. 

2. They give with solution of silver nitrate a light-yellow 
precipitate of silver bromide, insoluble in nitric acid, slightly 
soluble in ammonia water. 

3. Nitric acid, or chlorine added to solution of a bromide 
liberates bromine, which may be removed by shaking with ether. 

4. Free bromine imparts an orange color to mucilage of 
starch. 

5. Strong sulphuric acid dropped upon a dry bromide liber- 
ates reddish vapors of bromine. 

The oxygen acids of bromine are: 

HBrO, Hypobromous Acid, 
HBr0 3 , Bromic Acid, 
HBr0 4 , Perbromic Acid. 

These acids and their compounds are similar in method of 
preparation and properties to the corresponding compounds of 
chlorine. 

No oxides of bromine have ever been obtained. 

IODINE. 

Symbol, I. Atomic Weight, 126. Valence, I. 

Occurrence in Nature. Iodine occurs in combination as 

sodium, potassium, or magnesium iodide. In these forms it 

occurs in small quantity in certain mineral springs (Austria 

and Bavaria) and in sea water. The salts of iodine are absorbed 



THE NON-METALLIC ELEMENTS 1 43 

by sea weeds, and the iodine is largely obtained from the ash of 
these plants. 

Preparation. Kelp, or the ash of sea weeds, is washed with 
water in order to remove its soluble constituents ; the resulting 
liquid is evaporated to concentration and allowed to cool, when 
the chlorides and carbonate of sodium and potassium are re- 
moved by crystallization. The remaining mother-liquor is 
heated in a retort with the black oxide of manganese and sul- 
phuric acid, and the liberated iodine is condensed in a cooled 
receiver. 

Mn0 2 + 2H 2 S0 4 + 2NaI = Na 2 S0 4 + MnS0 4 + 2H 2 + I 2 . 

Iodine may also be liberated from its compounds by passing 
chlorine through solutions containing them. It is now prepared 
from the mother-liquor of Chili saltpeter, where it exists as the 
iodate. 

Properties. Iodine is a dark, bluish-black solid, forming 
crystalline scales, which have a distinct metallic lustre. It gives 
off a peculiar odor, resembling that of chlorine, stains the skin 
brown, and is corrosive to a less extent than bromine. Its 
specific gravity is 4.95; it fuses at a temperature of 114 , and 
boils at 180 . The vapor of iodine has a beautiful violet color. 
It volatilizes slowly at ordinary temperatures when exposed to 
the air. Iodine is only slightly soluble in water, about one in 
5,000 to 7,000 parts; the aqueous solution has a reddish-brown 
color. The solubility of iodine in water is greatly increased by 
the presence of the iodides of the alkalies, or hydriodic acid. 

It is soluble in about ten parts of alcohol — tincture of iodine — 
more soluble in ether, chloroform, and carbon bisulphide. In 
chemical properties iodine resembles chlorine and bromine, dif- 
fering from these elements in the intensity of its affinities, which 
are much weaker ; on this account it is liberated from combina- 
tion by these elements. 



144 TEXT-BOOK OF CHEMISTRY 

Iodine is largely used in medicine, both in the elementary 

state and in combination. It acts as a. corrosive irritant poison 

when the dose is excessive, and mucilage of starch is used as an 

antidote. 

Hydrogen Iodide, Hydriodic Acid, HI. 

Preparation. A glass tube is selected, a few fragments of 
phosphorus are placed in the bottom, then a layer of broken 
glass, then a layer of iodine. The tube is filled in this manner, 
with alternating layers of phosphorus, glass, and iodine, the 
glass being moistened with water. When gentle heat is applied, 
vapors of hydriodic acid escape, and may be collected by dis- 
placement of air through a delivery tube. The phosphorus and 
iodine combine, and in the presence of water form hydriodic 

acid: 

Pl3 + 3H 2 = H 3 P0 3 + 3HI. 

Hydriodic acid may be obtained in solution by the action of 
hydrogen sulphide upon iodine in the presence of water : 

I 2 + H 2 S + xH 2 = S + 2HI + *H 2 0. 

Properties. A colorless gas, having an irritating, suffocating 
odor, forms white fumes in the air. It is analogous in proper- 
ties to the corresponding compound of chlorine. Liquefied by 
pressure of 4 atmospheres at o° ; solidifies at — 55 °. Soluble 
in water; one volume taking up 427 volumes, imparting acid 
properties. Its aqueous solution undergoes decomposition by 
oxidation of the hydrogen, when the iodine is set free and 
dissolves, imparting a brown color. 

Diluted hydriodic acid, U. S. P., contains " not less than 10 
per cent., by weight, of the absolute acid." 

Tests for Hydriodic Acid and Iodides. 
1. They give a blue color with mucilage of starch and chlorine 
water. 



THE NON-METALLIC ELEMENTS I45 

2. To solution of iodide add chlorine water and shake with 
chloroform; the chloroform separates as a violet-colored layer. 

3. They giye a pale-yellow precipitate with solution of silver 
nitrate ; practically insoluble in diluted nitric acid, and ammonia 
water. 

4. They give a yellow precipitate with solution of lead 
acetate. 

5. They give a yellow precipitate, which turns red, with 
solution of HgCl 2 . 

6. Dry iodide with sulphuric acid gives vapors of iodine. 
The oxygen acids of iodine are: 

HIO3 — Iodic Acid. 
HIO4 — Periodic Acid. 

Iodic acid is formed by dissolving iodine in strong nitric acid, 
evaporating to dryness and heating to redness, and dissolving 
the resulting oxide of iodine I 2 5 in water. It is a white crys- 
talline soluble solid. 

These acids are analogous to the corresponding acids of 
chlorine, and their salts are prepared in the same way. 

FLUORINE. 

Symbol, F. Atomic Weight, 19. Valence, I. 

On account of its intense chemical activity it is extremely 
difficult to keep fluorine in the elementary state long enough 
to examine its properties. It was obtained free by Moissan in 
1887. 

Occurrence in Nature. Fluorine is found as the fluoride 
of calcium, CaF 2 , in minerals ; in small quantity as a constituent 
of bones, and the enamel of teeth. 

Preparation. By electrolysis of hydrogen fluoride in ves- 
sels of platinum at a temperature of about — 23 °, the element 
is obtained in a free state. . 

Properties. A greenish-yellow, tenuous gas; having a dis- 



I46 TEXT-BOOK OF CHEMISTRY 

agreeable and very irritating odor, producing inflammation of 
the air passages when inhaled, even in small quantity. 

It has a powerful affinity for nearly all the other elements, 
uniting with hydrogen with great violence, even at low tempera- 
tures, and combining with carbon, sulphur, phosphorus, boron, 
silicon, arsenic and calcium with production of flame. It com- 
bines with iron with incandescence, and attacks silver, lead and 
mercury. It decomposes water with production of hydrofluoric 
acid and liberation of ozone, in fact, it is the most active of the 
elements. 

Hydrofluoric Acid, Hydrogen fluoride, HF. Prepared by 
distilling calcium fluoride and sulphuric acid in platinum or 
leaden vessels. In properties, it is a colorless, extremely vola- 
tile, fuming, corrosive liquid. Its boiling point is 19 , specific 
gravity .98 at 12 . In order to recondense the gas it must be 
cooled to — 20 . It attacks glass and porcelain energetically 
and most metals; therefore, it has to be kept in vessels of 
caoutchouc. When dropped upon the skin it produces painful 
and indolent ulcers. It is used for etching glass. 



THE NON-METALLIC ELEMENTS 



147 



Fig. 35- 




Apparatus for Solution. — Test Tubes, Beakers, Retort Stand, Flasks. 
(After Rockwood.) 



I48 TEXT-BOOK OF CHEMISTRY 



Fig. 36. 




HEL. 



Apparatus for Filtration. (After Rockwood.) 



THE METALLIC ELEMENTS 1 49 



THE METALLIC ELEMENTS. 

General Properties. Only about one-half of the total num- 
ber of fifty-eight metallic elements are of sufficient importance 
to engage our attention. Many of them are exceedingly rare 
and are of interest only to the student of theoretical chemistry. 

The physical properties of the metals furnish their chief dis- 
tinguishing characteristics. They have a peculiar appearance 
known as metallic lustre due to their high degree of opacity and 
great power to reflect light. A smooth surface, however, is 
necessary to produce the lustrous appearance, and for this 
reason they generally appear as a black deposit when precipi- 
tated in a finely divided state. The most lustrous metals, such 
as gold and silver, lose this property when precipitated from 
solution in fine powder. 

The metals are good conductors of heat and electricity ; they 
present the properties of malleability, ductility and hardness 
to varying degrees ; they are generally fusible, and many of them 
can be volatilized. The specific gravities present a wide range, 
varying from .59 for lithium to 22.4 for osmium. 

Most of the metals have a gray or bluish-gray appearance, 
few of them having any decided color. Those showing a dis- 
tinct color are copper, which is red; and calcium, barium and 
gold, which show different shades of yellow. Silver is pure 
white. 

The metals form many compounds with non-metals by direct 
union, most of them uniting with phosphorus, sulphur, chlorine, 
bromine, iodine and oxygen. The oxides are usually basic in 
character, which distinguishes them strongly from the non- 
metals whose oxides are acidic. There are some few metals, 
however, which form acid oxides since there is no abrupt line 
of demarkation between metals and non-metals. 

Alloys. Metals show little tendency to combine among 



150 TEXT-BOOK OF CHEMISTRY 

themselves, though in some cases it is probable that a chemical 
compound is formed by fusing them together. An alloy is 
made by fusing two or more metals together, and it is believed 
to be partly a chemical compound and partly a mechanical mix- 
ture. In the alloy, we find the metallic character retained and 
about the average of the properties of its constituents; the 
fusing point and conductivity are reduced below the mean. 

Amalgams are alloys in which one of the constituents is mer- 
cury. 

Preparation of Metals. A great many of the metals occur 
in nature in the form of sulphide, oxide or carbonate, and on 
this account we can form general rules for their preparation. 
In order to prepare a metal from an ore in which it occurs as 
sulphide, the sulphide is roasted, or heated in air, thus forming 
the oxide and the oxide is then heated with carbon, thus 
liberating the metal. Let R stand for any metal, and the fol- 
lowing equation will represent the changes taking place : 

RS + Os = RO + S0 2 , 

RO + C = CO + R. 

When the metal occurs in nature as oxide or carbonate it 
is prepared by heating with carbon, thus : 

RCO3 + G = R + 3CO. 
Classification of the Metals. 

The metals may be classified in many different ways but the 
simplest and most convenient is based chiefly upon their analyt- 
ical reactions, as follows: 

Light Metals. In these the specific gravity is from .6 to 6; 
and the sulphides are soluble. 

Heavy Metals. In these the specific gravity is from 6 to 22 ; 
and the sulphides are insoluble. 

The metals are further subdivided into groups, thus : 



THE METALLIC ELEMENTS ' 1 5 1 

Alkali metals. Alkaline earth metals. 

K, Na, NH 4 , Li, Cs, Rb. Ba, Ca, Sr, Mg. 

Earth metals. Iron group. 

Al, and certain rare metals. Fe, Co, Ni, Mn, Cr, Zn. 
Lead group. Arsenic group. 

Pb, Cu, Bi, Ag, Hg, Cd. As, Sb, Sn, Au, Pt, Mo. 

The noble metals are mercury, silver, gold, platinum, palla- 
dium, rhodium, ruthenium, osmium, and iridium. These metals 
may be separated from their oxides (when oxides are formed) 
by simply heating to redness. 

ALKALI METALS. 

The metals potassium {rubidium, caesium), lithium, sodium, 
and the compound ammonium constitute the members of this 
group. They are decidedly the most basic of the metals in 
their character, and have been grouped together on account 
of great similarity in physical and chemical properties, both in 
the elementary state and in their compounds. 

They are silvery white metals, capable of fusion at a moder- 
ate temperature. When exposed to the air they quickly oxidize ; 
they decompose water at all temperatures, forming hydrox- 
ides, which dissolve to form an alkaline solution; for this rea- 
son called alkali metals. Their chemical affinities increase with 
increasing atomic weight. They form soluble oxides, hydrox- 
ides, carbonates, phosphates, sulphides, nitrates and halogen 
salts. They are the only metals whose hydroxides and carbon- 
ates are not decomposed by heat. Their hydroxides are known 
as caustic alkalies. They are all univalent. 

POTASSIUM (Kalium). 
Symbol, K. Atomic Weight, 39. Valence, I. 
Potassium was discovered by Sir Humphrey Davy in 1807, 
who obtained it by electrolysis of the moistened hydroxide. 



152 TEXT-BOOK OF CHEMISTRY 

Occurrences in Nature. This element is found in nature 
as the chloride and sulphate in large deposits in Stassfurt, and 
as the nitrate in some soils in hot countries. It occurs in these 
forms in certain mineral waters, and to some extent in sea 
water. It is found also as the double silicate of potassium and 
aluminum in granite rocks and feldspar. By the gradual dis- 
integration of these rocks the potassium is rendered soluble, 
and is carried into the soil, from which it is absorbed by grow- 
ing plants. In the tissues of plants it exists in combination with 
organic acids, as the tartrate, citrate, etc. When plants are 
burned the potassium present is converted into carbonate, and 
remains in the ash. By washing the ash of plants with water 
— or lixiviating — filtering and evaporating the solution to dry- 
ness, an impure potassium carbonate is obtained, known as 
crude potash. When crude potash is heated to redness, to expel 
organic matter, it is called pearlash. This salt was for a long 
time the source of all the compounds of potassium, but they are 
now chiefly prepared from the chloride, which is found in great 
abundance in nature. 

Preparation. Metallic potassium is obtained by heating the 
carbonate with carbon in iron retorts, condensing the volatilized 
metal in flat-shaped iron receivers, and cooling in rectified petro- 
leum. The chemical changes taking place are shown in the 

equation : 

K 2 C0 3 + C 2 = 3CO + K 2 . 

The distillation of potassium has to be conducted with a 
great deal of care on account of the formation of an explosive 
compound of the metal with carbon monoxide. It is also pre- 
pared by electrolysis of the fused hydroxide. 

Properties. A silvery-white solid, having a bright metallic 
lustre; soft enough to be easily cut with a knife. Its specific 
gravity is .86; fusing point 62.5 °. At a red heat it .volatilizes to 
a greenish vapor, when air is excluded, but when heated in the 
air it burns with a violet-colored flame, forming the oxide. 



THE METALLIC ELEMENTS ' I 53 

Potassium when exposed to the air becomes rapidly tarnished 
on account of its affinity for oxygen, and soon acquires a coat- 
ing of hydroxide by the simultaneous action of atmospheric 
moisture; therefore, in order to preserve it, it must be kept in 
a liquid destitute of oxygen, or in an atmosphere of hydrogen. 
It decomposes water with formation of the hydroxide and 
liberation of hydrogen, the chemical action being so intense as 
to cause the latter to take fire at the moment of liberation. 

It combines directly and energetically with the halogens. 

COMPOUNDS OF POTASSIUM. 

Potassium Oxide, or Monoxide, K 2 0. Formed by oxi- 
dation of thin sheets of the metal in dry air, or by heating the 
hydroxide with potassium : 

2KOH + K 2 = 2K 2 + H 2 . 

Properties. A white powder, having great affinity for water 
to form the hydroxide. Capable of fusion, and of being 
volatilized at a high temperature. The peroxide, K 2 2 , and 
tetroxide, K 2 4 , are known. 

Potassium Hydroxide, Caustic Potash, KOH. Preparation. 
By the action of the monoxide on water. By boiling a solution 
of potassium carbonate with calcium hydroxide : 

KsCOa + Ca(OH) 2 = 2KOH + CaCOs. 

The supernatant liquid is separated from the precipitated cal- 
cium carbonate by decantation, heated until water is expelled 
and allowed to solidify. 

Properties. A hard, white, crystalline mass, very deliques- 
cent, and soluble in four-tenths parts water, two parts alcohol. 
It melts to an oily liquid when heated, and may be poured into 
moulds to form pencils. At a red heat it volatilizes without de- 
composition. Caustic potash is a powerful base; destroys 



154 TEXT-BOOK OF CHEMISTRY 

organic matter, and combines with acids to form salts. It acts 
as a corrosive poison, dissolving the tissues and saponifying 
fats. Weak acids and oils are used as antidotes. The liquor 
potassse of the U. S. P. is a 5 per cent, aqueous solution of 
potassium hydroxide. 

The compounds of potassium with the halogens may be ob- 
tained by direct union of the elements, or by the action of 
halogen acids upon potassium hydroxide. They form cubical 
crystals, freely soluble in water, having a salty taste, and 
capable of fusion and volatilization by heat. 

Potassium Chloride, KC1, occurs abundantly in nature in 
an impure state in sea water, in mineral springs, and in the salt 
mines of Stassfurt, Germany. Prepared by recrystallization of 
the salt found in nature, or by neutralizing hydrochloric acid 
with potassium carbonate : 

2HCI + K 2 C0 3 = 2KCI + H 2 + C0 2 . 

Properties. White cubical crystals. Soluble in three parts 
water, insoluble in alcohol. When heated the salt melts, and at 
a red heat it volatilizes. It is largely used for preparing other 
potassium compounds. 

Potassium Iodide, KI. Prepared by dissolving iodine in 
solution of potassium hydroxide in sufficient quantity to form 
a permanent yellowish color. This forms a solution of the 
iodide and iodate of potassium, according to this equation : 

6KOH + 61 = 5KI + KIO3 + 3H 2 0. 

The liquid is then evaporated to syrupy consistency and 
mixed with wood charcoal, dried and heated to redness, when 
the iodate is converted into iodide, as shown by the equation : 

KI0 3 + 3C = KI + 3 CO. 

The residue is next washed with water, filtered and evap- 
orated for the formation of crystals. 



THE METALLIC ELEMENTS ' 1 55 

Properties. White, opaque, cubical crystals, or a white, 
granular powder ; saline taste, faintly alkaline reaction. Crys- 
tals white when obtained from alkaline solution, transparent 
when obtained from neutral solution. Soluble in .7 parts 
water, .5 parts boiling water, 12 parts alcohol, and 2.5 parts 
glycerine. The salt when exposed to the air assumes a slightly 
yellowish color from liberation of iodine. It should not give a 
blue color with mucilage of starch, showing absence of free 
iodine. Used largely in medicine. 

Potassium Bromide, KBr. Prepared like the iodide, ex- 
cept that bromine is used instead of iodine. 

Properties. Colorless, cubical crystals or a granular pow- 
der, neutral in reaction. The commercial salt is usually white 
and slightly alkaline. Soluble in 1.5 parts water, 180 parts 
alcohol, 4 parts glycerine. Used largely in medicine. 

Potassium Carbonate, K 2 C0 3 . {Salt of tartar.) 

Preparation. Obtained in an impure form by lixiviation of 
wood ashes, evaporating the liquid to dryness and heating to 
redness as <c pearlash." Also made by the Leblanc process from 
the chloride. (See sodium carbonate.) 

Properties. A white, granular, deliquescent power, soluble 
in water, of caustic taste and alkaline reaction. The salt can 
be obtained in a pure state by heating the bicarbonate thus : 

2KHCO3 = K 2 C0 3 + H 2 + CO* 

Potassium Bicarbonate, KHC0 3 . Prepared by passing 
carbon dioxide through a strong solution of potassium car- 
bonate when crystals of the salt separate. 

Properties. Colorless, flat, transparent crystals, slightly 
alkaline taste and reaction; soluble in 3 parts of water, in- 
soluble in alcohol. 

Potassium Nitrate, Nitre, Saltpeter, KN0 3 . Found in 
nature in the soil in hot countries, being formed by the decay 
of nitrogenous organic matter in the presence of potassium 
salts. 



I56 TEXT-BOOK OF CHEMISTRY 

Preparation. This salt is prepared by means of the nitre 
bed, which consists of heaps of nitrogenous organic matter — 
hides, horns, hoofs and flesh of dead animals — lime and earth. 
These are placed under a shed, watered with putrid urine and 
stirred from time to time to give access of the oxygen of the 
air. The chemical changes taking place here consist in the 
formation of ammonia, which is oxidized to nitric acid; the 
nitric acid uniting with lime forms calcium nitrate. The cal- 
cium nitrate is then washed out with water and decomposed 
with potassium carbonate, according to the equation : 

Ca(N0 3 ) 2 + K 2 C0 3 = CaCOs + 2KNO3. 

In this reaction, calcium carbonate precipitates, leaving po- 
tassium nitrate in solution. The solution is poured off and 
evaporated and potassium nitrate crystallizes out. 

Potassium nitrate is made also by action of potassium chloride 
on sodium nitrate in solution, thus: 

KC1 + NaN0 3 = NaCl + KN0 3 . 

When solution of these salts is concentrated by evaporation 
to a specific gravity of 1.5 the sodium chloride crystallizes out 
first, being no more soluble in hot than cold water. The 
mother-liquor is then drawn off and potassium nitrate crystal- 
lizes upon cooling. 

Properties. Colorless, transparent, six-sided rhombic prisms, 
or a crystalline powder; cooling saline taste, neutral reaction, 
soluble in 3.6 parts cold water, .4 parts boiling water, only 
slightly soluble in alcohol. The salt melts when heated to 353 °, 
and at a higher temperature gives off oxygen. A strong oxidiz- 
ing agent. Used in medicine ; used as a preservative for meats ; 
and used in making gunpowder. 

Potassium Sulphate, K 2 S0 4 Occurs in the salt mines of 
Stassfurt, and in plants. 

Preparation. By action of sulphuric acid on the chloride, 

thus: 

2KCI + H 2 S0 4 = K 2 S0 4 + 2HCI. 



THE METALLIC ELEMENTS 157 

Properties. Anhydrous, rhombic prisms. Soluble in nine 
parts water ; insoluble in alcohol ; slightly bitter taste. 

Potassium Bisulphate, Acid Sulphate of Potassium, KHS0 4 , is ob- 
tained by the action of one molecule of sulphuric acid on one molecule 
of potassium chloride, thus : 

H 2 S0 4 + KC1 = KHSO4 + HC1. 

Potassium Sulphite, K2SO3.2H2O, is made by the action of sulphurous 
acid on potassium carbonate, thus: 

H 2 S0 3 + K.0CO3 = K 2 S0 3 + H 2 +C0 2 . 

Potassa Sulphurata, Liver of Sulphur, is a mixture of sul- 
phides of potassium with sulphate and thiosulphate. 

Prepared by heating a mixture of sulphur and potassium 
carbonate. 

Properties. Liver-brown, irregular masses when fresh. 
Gradually turns yellowish-green, and finally gray by exposure, 
absorbing carbon dioxide. 

Potassium Chlorate, KC10 3 . Prepared by action of chlo- 
rine on hot solution of potassium hydroxide. Crystals are 
formed when the liquid cools. 

6KOH + 3 C1 2 = 5KCI + KCIO3 + 3H 2 0. 

Properties. Shining, transparent, tabular crystals or a 
white granular powder, soluble in sixteen parts of water, in- 
soluble in absolute alcohol, cooling, saline taste. Gives up 
oxygen by heat. A strong, oxidizing agent. 

Potassium Hypophosphite, KH 2 P0 2 . Prepared by action 
of calcium hypophosphite on potassium carbonate in solution, 
thus: 

Ca (H 2 P0 2 ) 2 + K 2 C0 3 = 2KH 2 P0 2 + CaCOs. 

The clear liquid is poured off and evaporated for crystals at 
a temperature not over ioo°. 

Properties. A granular, crystalline, deliquescent powder, 



158 TEXT-BOOK OF CHEMISTRY 

soluble in water and in alcohol. Explodes violently when 
rubbed with oxidizing agents. 

Tests for Potassium. 

1. To solution of potassium salt add a few drops of hydro- 
chloric acid and of perchloride of platinum, a granular, yellow 
precipitate forms. 

2. Solution of tartaric acid gives a colorless granular pre- 
cipitate. 

3. Sodium cobaltic nitrite in neutral solution gives a yellow 
precipitate. 

4. Potassium colors the Bunsen burner flame violet, obscured 
by sodium, but can be seen through blue glass. 

SODIUM (Natrium). 
Symbol, Na. Atomic Weight, 23. Valence, I. 
Discovered by Sir Humphrey Davy at about the same time 
and by the same means as potassium. 

Occurrence in Nature. As the chloride, in rock salt, in 
large deposits in the earth, in mineral waters and in sea water. 
As the sulphate, carbonate and borate in minerals or in water. 
It is widely distributed in nature. 

Preparation. According to the general rule, for preparing 
the metals, by heating the carbonate with carbon in an iron 
retort : 

Na 2 C0 3 + Q = 3CO + Na 2 . 

The vapors of the metal are condensed in an iron receiver, 
and cooled under rectified petroleum. 

Properties. Like potassium in appearance and consistency. 
It fuses at 95 .6° ; volatilizes at a red heat to a colorless vapor, 
which burns in the air with a yellow flame. Its specific gravity 
is .972. Sodium soon becomes tarnished by oxidation when 
exposed to the air, and has to be kept in petroleum. It acts upon 



THE METALLIC ELEMENTS 159 

water like potassium, but less energetically, forming the hydrox- 
ide with liberation of hydrogen, which does not take fire unless 
the movements of the mass are restrained. 

COMPOUNDS OF SODIUM. 

Sodium Oxide, Na 2 0. Prepared like the corresponding 
compound of potassium. 

In Properties it is a gray, fusible, soluble mass. 

Sodium Dioxide, Na 2 2 , is made by heating the metal in a 
stream of oxygen. It is a white powder, which decomposes 
when mixed with water into sodium hydroxide and water. 
When dissolved in water to which an acid has been added it 
forms peroxide of hydrogen and a sodium salt. This compound 
is used as a bleaching, disinfecting and Oxidizing agent. 

Sodium Hydroxide, Caustic Soda, NaOH. In method of 
preparation and properties like the hydroxide of potassium. 

Sodium Chloride, Common Salt, NaCl. Found in large 
deposits in the earth, and obtained from this source by solu- 
tion and crystallization. Found in sea water and removed by 
evaporation and crystallization, the remaining mother-liquor 
being known as " bitturn," and used for preparation of bromine. 

Sodium chloride is found in all parts of the animal system, 
where it facilitates the process of osmosis, and contributes to 
the formation of hydrochloric acid of the gastric juice. 

Properties. Colorless, cubical crystals, which arrange them- 
selves into pyramids. It has a salty taste, a neutral reaction, 
and is soluble in about 2.8 parts cold, or 2.5 hot water. It is 
anhydrous. The pure salt is not deliquescent, but the presence 
of magnesium chloride as an impurity causes it to absorb mois- 
ture from the air. 

Sodium, bromide, iodide and chlorate are prepared like the 
corresponding compounds of potassium. The chlorate of 
sodium is more soluble in water than the potassium compound. 



l60 TEXT-BOOK OF CHEMISTRY 

Sodium Sulphate, Glauber's salt, Na 2 S0 4 . Found in nature 
with the chloride, and in some mineral waters. 

Preparation. By heating the chloride with sulphuric acid, 
and purifying by recrystallizing : 

2NaCl + H 2 S0 4 = Na 2 SO, + 2HCI. 

Properties. Sodium sulphate forms large, colorless crys- 
tals, containing 10 molecules water of crystallization; soluble 
in 2.8 parts cold water, and in .47 parts boiling water. Used as 
a purgative. 

Sodium Bisulphate, NaHS0 4 , made by the action of one 
molecule of sodium chloride upon a molecule of sulphuric acid, 
is a colorless, crystalline, soluble salt. 

Sodium Sulphite, Na 2 S0 3 , and Sodium bisulphite, NaHS0 3 . 
When a cold solution of sodium carbonate is saturated with sul- 
phur dioxide the bisulphite separates in turbid crystals. 

Na.COs + 2S0 2 + H 2 = 2NaHS0 3 + C0 2 . 

By adding sodium carbonate to this bisulphite the normal 

sulphite is obtained as a crystalline, soluble salt, of alkaline 

reaction. 

2NaHS0 3 -f Na 2 C0 3 = 2Na 2 S0 3 + H 2 + C0 2 . 

Sodium Thiosulphate {Sodium hyposulphite), Na 2 S 2 3 . 
Prepared by boiling a solution of sodium sulphite with sul- 
phur and crystallizing : 

Na 2 S0 3 + S = Na 2 S 2 3 . 

Properties. Large, colorless, deliquescent, soluble crystals, 
containing five molecules water of crystallization. Used in 
photography to dissolve the halogen salts of silver. 

Sodium Carbonate, Washing Soda, Sal. Soda, Na 2 C0 3 - 
ioH 2 0. Found in nature in ash of plants, in mineral waters, 
in the soil in rainless countries. 

Preparation. By the Leblanc process, which consists in heat- 



THE METALLIC ELEMENTS l6l 

ing sodium chloride with sulphuric acid in furnaces, and form- 
ing sodium sulphate, or " salt cake " : 

2NaCl + H 2 S0 4 = Na 2 S0 4 + 2HCI. 

The sodium sulphate is then heated in a furnace with lime- 
stone (calcium carbonate) and coal (carbon) to form " black- 
ash," which contains the sodium carbonate and calcium sul- 
phide : 

Na 2 S04 + 4C + CaCOs = Na 2 C0 3 + 4CO + CaS. 

The " black-ash " is washed with water when calcium sul- 
phide with calcium oxide forms an insoluble calcium oxysul- 
phide, and sodium carbonate dissolves out, and is crystallized by 
evaporating the solution. 

The ammonia process , or Solvay method, consists in the 
double decomposition effected by the action of ammonium bicar- 
bonate on sodium chloride under pressure, and then heating 
the resulting sodium bicarbonate to convert it into carbonate 

thus: 

NH4HCO3 + NaCl = NaHCOs + NH*C1. 

2NaHC0 3 = Na 2 C0 3 + H 2 + C0 2 . 

Properties. Large, colorless, odorless crystals; specific 
gravity, 144; soluble in 1.6 parts of water, 1.02 parts of gly- 
cerine, and insoluble in alcohol. The salt has an alkaline taste 
and reaction, and loses water when exposed to the air. Used 
largely for cleansing purposes, in the manufacture of soap, and 
in medicine. 

Sodium Bicarbonate, Bread soda, Baking soda, NaHC0 3 . 
Found in nature in Vichy water. 

Prepared by the ammonia soda process, or by passing carbonic 
acid gas over the carbonate containing some water, thus : 

Na 2 C0 3 + H 2 + C0 2 = 2NaHC0 3 . 

Properties. A white powder, soluble in water, insoluble in 



1 62 TEXT-BOOK OF CHEMISTRY 

alcohol. The aqueous solution is faintly alkaline, and is de- 
composed to carbonate by boiling. 

Sodium Nitrate, NaNO s . Occurs in nature in large deposits 
in South America, Chili, Peru, Brazil. 

Prepared by purifying the crude salt by crystallization from 
water. 

Properties. Colorless, odorless, transparent crystals ; freely 
soluble in water, slightly soluble in alcohol. Deliquescent. 
Used largely for making nitric acid and potassium nitrate. 

Sodium Orthophosphates. Three of these are known : 

Monosodium phosphate, NaH 2 P04.H 2 0. 
Disodium phosphate, Na 2 HP04.i2H 2 0. 
Trisodium phosphate, Na 3 P04.i2H 2 0. 

The last of these compounds is formed by adding caustic soda 
in excess to orthophosphoric acid. It is an unstable compound. 

The second compound is the one commonly used in medicine 
as Sodium Phosphate, Disodium hydrogen phosphate, Na 2 - 
HP0 4 .i2H 2 0. 

Prepared by adding sodium carbonate to orthophosphoric 
acid to faintly alkaline reaction and crystallizing. 

Properties. Large, colorless, odorless crystals, having a 
cooling, saline taste; soluble in water, insoluble in alcohol, and 
strongly efflorescent. Used as a purgative, and as a reagent. 

The first compound, monosodium phosphate, is formed by 
adding phosphoric acid to the disodium phosphate to feebly acid 
reaction, and crystallizing. 

Sodium Borate, Borax, Na 2 B 4 7 .ioH 2 0. Found in nature 
in certain lakes — Thibet, Nevada, California — known as tincal 
in the crude state. 

Prepared by crystallization from water. 

Properties. Colorless, transparent crystals, or white powder ; 
slightly alkaline taste and reaction. Slightly efflorescent, soluble 



THE METALLIC ELEMENTS 1 63 

in water, insoluble in alcohol, soluble in glycerine. Loses water 
when heated, and finally forms borax bead. Used in medicine 
and in the arts. 

Sodium Hypochlorite, NaClO. Employed in solution in 
" liquor sodae chlorinatae," or Labaraque's solution. 

Prepared by the action of calcium hypochlorite on sodium 
carbonate in solution. Used largely as an antiseptic and disin- 
fectant. 

Sodium Hypophosphite, NaH 2 P0 2 .H 2 0. Preparation and 
properties like the corresponding salt of potassium. 

Tests for Sodium. 

1. All salts of sodium are soluble except the pyroantimoniate, 
therefore potassium pyroantimoniate is sometimes used as a 
reagent to precipitate its salts. 

2. Sodium compounds color the flame yellow. 

LITHIUM. 

Symbol, Li. Atomic Weight, 7. Valence, I. 

Occurs in nature as silicate and carbonate in minerals and 
some mineral waters. Prepared by electrolysis of fused 
chloride. 

Properties. A white, soft, light metal, resembling potas- 
sium. Specific gravity .59. 

The bromide and carbonate are the official inorganic salts. 
Bromide made by dissolving the carbonate in hydrobromic acid 
and crystallizing. 

Properties. A white, granular, soluble powder. 

The carbonate made by precipitating a solution of lithium 
salt with sodium carbonate. 

Properties. A white powder, soluble in 80 parts of water, 
insoluble in alcohol. 

The compounds of lithium are like those of potassium, but 
less soluble. 



I64 TEXT-BOOK OF CHEMISTRY 

Tests, i. Sodium phosphate, added to concentrated solution 
of lithium salts, gives a white precipitate on boiling. 
2. Lithium salts color the flame crimson. 

AMMONIUM. 
Formula, NH 4 . Molecular Weight, 18. Valence, I. 
This compound radical is formed from ammonia, NH 3 , by 
its action upon acids, in which the hydrogen of the acid is re- 
tained, thus : 

NH 3 + HC1 = NH4CI. 

The chemical behavior of the ammonium radical is similar 
to that of an alkali metal, the radical acting like a single atom 
of a metal. The properties of its compounds show great re- 
semblance to the compounds of potassium and sodium, and its 
metallic character is so well established that it is classed among 
the alkali metals. 

Whenever an attempt is made to separate the ammonium 
radical, it decomposes into ammonia and hydrogen, so that this 
radical has never been obtained free. The formation of an 
ammonium amalgam is as near an approach to its separation 
as has yet been attained. Though ammonium amalgam has 
a decidedly metallic appearance, this interesting body soon de- 
composes into ammonia, hydrogen and mercury. The amalgam 
is made by dissolving metallic sodium in an equal amount of 
mercury, and adding the sodium amalgam to a strong solution 
of ammonium chloride. The chemical reaction is represented 
in the equation, thus : 



NaHg 


+ 


NH^Cl 


= 


NH 4 Hg 


+ 


NaCl. 


Sodium 




Ammonium 




Ammonium 




Sodium 


amalgam 




chloride 




amalgam 




chloride 



The ammonium compounds are obtained from the ammoniacal 
liquor of the gas-works, this liquid consisting of a solution of 
ammonium hydroxide in water. By saturating ammonium hy- 



THE METALLIC ELEMENTS 1 65 

droxide with various acids the corresponding salts may be 
formed. 

Ammonium Chloride, Sal-ammoniac, NH 4 C1. This salt is 
sometimes found in volcanic districts. Preparation. Ammo- 
nium chloride is formed by the action of hydrochloric acid upon 
the ammoniacal liquor of the gas-works, evaporating to dryness 
and further purifying by subliming. In properties it is found 
either in the form of a granular crystalline powder or in the 
form of tough crystalline masses. The salt is soluble in 3 parts 
cold water, one part hot water; it has a salty, disagreeable, 
metallic taste; when heated it sublimes without melting, and 
dissociates at a high temperature into NH 3 and HC1. 

Ammonium Bromide, NH 4 Br, and Ammonium Iodide, 
NH\J, are prepared by adding solution of ammonium sulphate 
to potassium bromide for the first, and solution of ammonium 
sulphate to potassium iodide for the second, thus : 

(NHO2SO4 + 2KBr = K 2 S0 4 + 2NH 4 Br. 

Alcohol is then added to the mixture which precipitates potas- 
sium sulphate ; the clear liquid is filtered off and evaporated, to 
obtain the ammonium salt. 

Properties. Both of these salts are granular, crystalline 
solids; having a salty taste, and freely soluble in water or 
alcohol. 

Decolorized tincture of iodine, made by adding ammonia water to tinc- 
ture of iodine, contains ammonium iodide, ammonium iodate, and nitro- 
gen iodide. 

Ammonium Carbonate (Sesqnicarbonate) , NH 4 NH 2 C0 2 . 
NH 4 HC0 3 . The formula for this compound shows that it is 
a double salt, made up of two compounds, ammonium carba- 
mate, NH 4 NH 2 C0 2 , and ammonium bicarbonate, NH 4 HCO s . 
Ammonium carbamate is a salt of carbamic acid, H NH 2 C0 2 , 
in which the hydrogen has been replaced by the radical NH 4 . 



1 66 TEXT-BOOK OF CHEMISTRY 

This acid will be considered in the study of organic chemistry. 
Preparation. Ammonium carbonate is obtained by sublim- 
ing a mixture of ammonium chloride and calcium carbonate, 
according to the following equation : 

4 NH 4 C1 + 2CaC0 3 = NH 4 NH 2 C0 2 .NH 4 HC0 3 + NH 3 + H 2 + 2CaCl 2 . 

Properties. Ammonium carbonate occurs in colorless, crys- 
talline masses ; having an alkaline taste and reaction, the odor 
of ammonia, and being soluble in water. By exposure to air the 
salt gradually undergoes decomposition, the crystals becom- 
ing covered with a white coating until they gradually fall to a 
white, granular powder. This decomposition consists in elimi- 
nation of the ammonium carbamate from the molecule, which 
escapes as 2NH3 and C0 2 , leaving ammonium bicarbonate be- 
hind as the white granular powder. 

The tendency of ammonium carbonate to undergo decom- 
position requires the exercise of care in selecting the salt for 
use in medicine ; the undecomposed crystals alone should be 
used for this purpose, and they may be easily recognized by 
their colorless, crystalline, semitransparent appearance. 

The normal carbonate of ammonium, (NH 4 ) 2 C0 3 , can be 
formed from the sesquicarbonate by dissolving this salt in 
water and adding ammonia water to the solution. When ammo- 
nium sesquicarbonate is dissolved in water the carbamate portion 
of the molecule is converted into normal salt, and when ammonia 
water is added to this solution the remaining portion of the 
molecule is converted into normal ammonium carbonate. These 
chemical changes are represented in the following equations : 

NH 4 NH 2 C0 2 .NH 4 HC0 3 + H 2 = (NH 4 ) 2 C0 3 + NH 4 HC0 3 . 

( NH 4 ) 2 C0 3 + NH 4 HC0 3 + NH 4 OH = 2 ( NH 4 ) 2 C0 3 + H 2 0. 

Ammonium carbonate is used in medicine and as a chemical 
reagent. 



THE METALLIC ELEMENTS 1 67 

Aromatic Spirit of Ammonia is a solution of normal ammo- 
nium carbonate in diluted alcohol flavored with essential oils. 

Ammonium Sulphate, (NH 4 ) 2 S0 4 ; Ammonium Nitrate, 
NH 4 N0 3 ; Ammonium Nitrite, NH 4 N0 2 ; Ammonium Phos- 
phate, (NH 4 ) 2 HP0 4 . These salts are prepared by the action 
of the corresponding acid upon ammonia water, evaporating 
carefully and crystallizing. They are all white, solid, soluble 
salts. 

Ammonium nitrate decomposes, when heated, into nitrogen 
monoxide, N 2 0, and water, and is used in making " laughing 
gas." 

Ammonium nitrite when heated decomposes into nitrogen 
and water. 

Ammonium Sodium Hydrogen Phosphate, Microcosmic 
Salt, Salt of Phosphorus, NH 4 NaHP0 4 is found in guano and 
decaying urine. 

Prepared by mixing solutions of sodium phosphate and 
ammonium chloride and crystallizing: 

Na 2 HP0 4 + NH 4 C1 = NH 4 NaHP0 4 + NaCl. 

Properties. Granular, prismatic crystals, very soluble. Used 
in chemical analysis. 

Ammonium Hydrogen Sulphide, Ammonium Sulphydrate 
or Hydrosulphide, NH 4 HS. A salt formed by replacement of 
one of the hydrogen atoms of hydrogen sulphide, H 2 S, with 
the ammonium radical. 

Prepared by passing hydrogen sulphide into dilute ammonia 
water : 

NH 4 OH + H 2 S = NH 4 HS + H 2 0. 

Properties. Usually seen in the form of solution which is 
colorless or has a slightly greenish tinge; it has the odor of 
ammonia and of hydrogen sulphide. When ammonia water is 
added to this solution it is converted into normal ammonium 
sulphide, thus : 

NH 4 HS + NH^OH = (NH 4 ) 2 S + H 2 0. 



1 68 TEXT-BOOK OF CHEMISTRY 

These salts may be obtained in the form of a white crystal- 
line mass, which soon decomposes. Ammonium sulphide is very 
largely used as a reagent for precipitation of the heavy metals. 

Tests for Ammonium Compounds. 
i. All the compounds of ammonium are volatile, either with 
or without decomposition. 

2. When heated with alkalies, ammonia gas is given off. The 
ammonia gas may be recognized by its odor; by its action on 
moistened litmus paper, which it turns blue ; by the white fumes 
produced in the presence of hydrochloric acid. 

3. Solution of perchloride of platinum and hydrochloric acid 
give a fine granular yellow precipitate. 

4. Nessler's reagent 1 gives a reddish-brown color or precipi- 
tate. 

5. Sodium cobaltic nitrite in neutral or acid solution gives a 
yellow precipitate. 

Analytical Reactions. 

A. Directions for the detection of one of the metals, potass- 
ium, sodium or ammonium in aqueous solution. 

1. Take a small portion of the solution (about 2 c.c.) in a 
test-tube, add a few drops of solution of caustic soda and heat 
gently in the flame of the Bunsen burner. The odor of am- 
monia will indicate the presence of ammonium compounds. 

2. If ammonium be absent, take another portion of the solu- 
tion in a test-tube and add a few drops of hydrochloric acid and 

1 Nessler's Reagent is made by adding to a solution of 5 grammes of 
potassium iodide in hot water, a hot solution of mercuric chloride — 2.5 
grammes in 10 c.c. water. To the turbid red mixture is added a solu- 
tion containing 16 grammes of potassium hydroxide in 40 c.c. of water, 
and the whole is diluted to 100 c.c. This mixture is allowed to stand 
and the clear supernatant liquid is decanted for use. The reagent im- 
proves by keeping. 



THE METALLIC ELEMENTS 1 69 

perchloride of platinum. A granular yellow precipitate indi- 
cates the presence of potassium. 

The perchloride of platinum test for potassium cannot be ap- 
plied in the presence of ammonium salts. 

3. The loop of a platinum wire dipped in a little hydrochloric 
acid and then into some of the solution will give the intense 
yellow light of sodium, when held in the flame, if that element 
be present. 

B. Directions for detection of one, two or all three of the 
metals potassium, sodium or ammonium in aqueous solution of 
their salts. 

1. Test a small portion of the original solution for ammonium 
compounds, as directed in " I " of the foregoing experiments. 
If ammonium salts be present make a note of the fact and pro- 
ceed to remove the salts of this element by evaporating the 
original solution to dryness in a porcelain dish, and then care- 
fully heating the dry residue in a fume chamber until white 
fumes of ammonium salts cease to be evolved. 

2. After the contents of the dish have cooled, the residue is 
dissolved in a small quantity of water and tested for potassium 
by the perchloride of platinum test. In the absence of ammo- 
nium the original solution may be tested at once for potassium. 

3. Apply the flame test to some of the original solution for 
sodium. 



I70 TEXT-BOOK OF CHEMISTRY ' 

MAGNESIUM GROUP. 
MAGNESIUM. 

Symbol, Mg. Atomic Weight, 24. Valence, II. 

Magnesium and the rare metal Beryllium form a group of 
elements known as the magnesium group. They decompose 
hot water slowly, with evolution of hydrogen. They form in- 
soluble oxides, hydroxides, carbonates, phosphates and arsen- 
ates. 

These metals resemble zinc in the solubility of the sulphate 
and the volatility of the chloride, but differ from that metal in 
the fact that the sulphide is not precipitated by ammonium sul- 
phide. 

Magnesium is found abundantly in nature and widely dis- 
tributed. In the mineral kingdom it is found as sulphate, chlo- 
ride, carbonate, silicate and phosphate. As carbonate it is found 
in magnesite; as double carbonate of magnesium and calcium, in 
dolomite; as silicate, it is found in meerschaum, talc, asbestos, 
soapstone, etc. It is found in certain mineral waters known as 
bitter waters, as chloride and sulphate. In the animal and vege- 
table kingdoms magnesium occurs as carbonate in bones, and 
as phosphate in cereals ; also with vegetable acids in plants. 

Preparation. By electrolysis of the fused chloride, or by 
heating the chloride with sodium. 

Properties. A bright, silvery- white metal; sp. gr. 1.75; 
tenacious, ductile ; when heated may be rolled into ribbon or 
drawn into wire. It melts at 800 °, and volatilizes at a red heat ; 
oxidizes in moist air and becomes covered with a coating of 
oxide and carbonate; burns when heated in air with intense 
white light forming the oxide which is non-fusible. It decom- 
poses hot water ; is dissolved by dilute acids, but not affected by 
alkalies. It is bivalent in its compounds. Used in photograph- 
ing dark chambers. 



THE METALLIC ELEMENTS \J\ 

Magnesium Oxide, Calcined Magnesia, MgO. (Magnesia.) 
Preparation. By burning magnesia, or by heating the car- 
bonate or hydroxide. 

MgC0 3 = MgO + C0 2 . 

Properties. A white, amorphous, insoluble powder; unites 
with water to form the hydroxide. 

Magnesia occurs in two forms, light and heavy oxide, made 
by heating the light and heavy carbonate, respectively. 

Magnesium Hydroxide, Mg(OH) 2 . 

Preparation. By adding KOH, or NaOH to solution of a 
magnesium salt, collecting, washing and drying the precipitate. 

Properties. A white, amorphous powder, nearly insoluble in 
water; soluble in solution of ammonium chloride. Absorbs 
C0 2 from air to form carbonate. 

Milk of Magnesia is a white, opaque liquid, consisting of 
magnesium hydroxide suspended in water. 

Magnesium Chloride, MgCl 2 . Found in mineral springs 
in small quantity. 

Prepared by dissolving the carbonate or hydroxide in HC1, 
and evaporating. Crystallizes with 6 molecules of water, freely 
soluble, and deliquescent. When heated to drive off the water 
of crystallization it decomposes. To obtain the anhydrous salt 
evaporate mixed solutions of MgCl 2 and NH 4 C1 to dryness, and 
heat to 460 , when the water and ammonium chloride are driven 
off, leaving the anhydrous salt in leafy crystals. 

Magnesium Carbonate, MgCO s (Magnesia Alba, Light 
Magnesia). Occurs in nature as magnesite in crystalline com- 
pact masses, and with calcium in dolomite. The official car- 
bonate is a mixture of carbonate and hydroxide. 

Prepared by boiling solution magnesium sulphate and solu- 
tion sodium carbonate, collecting, washing and drying the pre- 
cipitate : 



172 TEXT-BOOK OF CHEMISTRY 

SMgSO* + 5Na 2 C0 3 + 6H 2 = 5Na 2 S0 4 + 4MgC0 3 .Mg(OH) 2 .5H 2 

+ C0 2 . 

If the above mixture of precipitate and solution be evapor- 
ated to dryness and the sodium sulphate be washed out with 
water, the remaining magnesium carbonate constitutes the 
dense, or heavy magnesium carbonate. 

In properties magnesium carbonate is a white, amorphous, 
insoluble powder. By suspending the normal salt in water and 
passing carbon dioxide through the mixture, crystals of normal 
carbonate form and separate. 

Magnesium Sulphate, Epsom Salt, MgS0 4 . Found in sea 
water, in mineral springs, and in the mineral kieserite. 

Prepared by action of sulphuric acid on the carbonate and 
evaporating the resulting solution to obtain crystals. 

MgCOs + H 2 S0 4 = MgS0 4 + C0 2 + H 2 0. 

Properties. Colorless prismatic crystals, containing 7 mole- 
cules water of crystallization. Saline, bitter taste, freely soluble 
in water (2 parts at o°), neutral reaction. At 150 loses all the 
water of crystallization but one molecule, which comes off at 
200 — this last molecule known as the water of constitution. 
Use as a purgative in medicine. (Crystals isomorphous with 
the sulphate of zinc.) 

Magnesium. Phosphate, MgHP0 4 , forms in colorless crys- 
tals when sodium phosphate is added to a solution of magnesium 
sulphate. When ammonia water is added to the solution of 
magnesium sulphate and sodium phosphate solution is poured 
in, a double compound of MgNH 4 P0 4 precipitates. This mag- 
nesium ammonium phosphate is slightly soluble in water, but 
insoluble in ammonia water. This reaction used as a test for 
magnesium. 

Tests for Magnesium. 

(1) NaOH, KOH, or NH 4 OH, give precipitate of 
Mg(OH) 2 , white and gelatinous, insoluble in excess, but 
soluble in solution of NH 4 C1, or ammonium salts. 



THE METALLIC ELEMENTS I 73 

(2) K 2 C0 3 , or Na 2 CO s gives, when heated with Mg com- 
pounds, white precipitate of carbonate. (NH 4 ) 2 C0 3 gives no 
precipitate. 

(3) Add sol. NH 4 C1, NH 4 OH and Na 2 HP0 4 ; a white pre- 
cipitate of MgNH 4 P0 4 forms : 

Na 2 HP0 4 + MgS0 4 + NH.OH = MgNH 4 P0 4 + Na 2 S0 4 + H 2 0. 

BERYLLIUM. 

Symbol, Be. Atomic Weight, 9. Valence, II. 

Occupies a position in this group similar to that held in the group 
of alkalies by lithium. 

Occurs in nature as silicate. 

Prepared by heating the chloride with Na. 

Properties. A silvery-white metal, malleable and ductile, little affected 
by air. 

Its salts resemble those of Mg. They have a sweet taste, and for 
this reason the element is sometimes called glucinum. 

Only of scientific interest. 

ALKALINE EARTH METALS. 

Calcium, Ca" = 40. Strontium, Sr" = 87. Barium, Ba" 
= 136. The metals of this group are called alkaline earth 
metals because they resemble in their properties the alkalies, on 
the one hand, and the earths on the other. This is shown 
very strongly in the oxides which like those of alkalies form 
hydroxides with water, and like those of the earths can be made 
from the hydroxide. With increase of atomic weight from cal- 
cium to barium their chemical energy and basic properties be- 
come greater. They decompose water with liberation of hydro- 
gen, as do the alkalies, but differ from them in forming in- 
soluble carbonates and phosphates and almost insoluble sul- 
phates. They differ from the earth metals by the solubility of 
their hydroxides. They are all bivalent. 



1/4 TEXT-BOOK OF CHEMISTRY 

CALCIUM. 

Symbol, Ca. Atomic Weight, 40. Valence, II. 

Occurrence in Nature. Calcium is widely distributed over 
the surface of the earth. It occurs as calcium carbonate in 
limestone, marble and chalk ; as sulphate in gypsum and ala- 
baster ; as phosphate it constitutes apatite ; as fluoride it is found 
in fluorspar ; as silicate in rocks. Calcium is found in the bones 
and nervous tissues of animals as phosphates ; also in plants in 
the same form of combination, and in union with organic acids. 

Preparation. On account of the infusibility of the oxide, 
calcium is more difficult to separate than the alkalies. It is 
usually prepared by electrolysis of the fused chloride, since the 
oxide when heated with carbon will not avail on account of its 
great infusibility. 

Properties. A yellow shining metal, resembling gold, 
quickly tarnishing by exposure to moist air. It decomposes 
water, is easily fused, and when heated in air it burns with a 
yellow flame. 

COMPOUNDS OF CALCIUM. 

The halogen salts are prepared by dissolving the oxide or 
carbonate in the haloid acids, or by direct union of calcium 
with the elements. The metal burns in an atmosphere of 
chlorine, bromine or iodine vapors. 

Calcium Chloride, CaCl 2 . This salt crystallizes from 
aqueous solution with six molecules of water in large deliques- 
cent prismatic crystals. When heated it melts in its water of 
crystallization, and at 200 becomes anhydrous as a white porous 
mass. The dry salt has strong affinity for water and is largely 
used for drying gases. Calcium chloride is often used for 
production of low temperature by dissolving hydrous salt in 
water ; calcium chloride and snow, or powdered ice, gives a 
temperature of — 48 C. 



THE METALLIC ELEMENTS 175 

The bromide and iodide are similar in physical and chemical 
properties to the chloride. 

Calcium Oxide, CaO, Burned lime, Quick-lime. May be 
made by heating the nitrate or carbonate. Generally prepared 
by burning the carbonate as found in limestone (CaC0 3 ) in 
lime-kilns, at a temperature of 8oo° C. 

CaCOs = CaO + C0 2 . 

The limestone retains its original size and shape but loses 
weight. 

Properties. Calcium oxide occurs as a white, odorless, amor- 
phous, infusible mass; having an alkaline taste and reaction. 
It has a powerful affinity for water with which it unites and falls 
to a grayish-white powder of calcium hydroxide, and it is then 
designated by the term slaked lime. Air slaked lime is formed 
by exposure of calcium oxide to the air, when it absorbs water 
and carbon dioxide, forming the hydroxide and carbonate. The 
calcium light is obtained by causing the flame of the oxyhy- 
drogen blowpipe to fall upon lime, thus heating the salt to the 
degree of incandescence. 

Calcium dioxide can be precipitated by adding H 2 2 to lime 
water. 

Calcium Hydroxide, Slaked Lime, Ca(OH) 2 , is a grayish- 
white, amorphous powder; it forms a paste with water, known 
as milk of lime ; it is slightly soluble in water, about one part in 
760 of water, more soluble in cold than hot water. 

Lime Water is prepared by shaking one part of calcium 
hydroxide with 30 parts of water, allowing the lime to settle 
and pouring off the clear liquid; to the residue, 300 parts of 
pure water are added, the mixture thoroughly shaken and 
allowed to settle, the clear liquid is then decanted for use. 
Lime water is a clear, colorless liquid ; having a feebly alkaline 
taste and reaction; it absorbs carbon dioxide gas from the air 



I76 TEXT-BOOK OF CHEMISTRY 

and forms a thin transparent pellicle, or crust, of calcium car- 
bonate upon its exposed surface. A stream of carbon dioxide 
passed through the liquid causes precipitation of the calcium 
as carbonate. 

Calcium Carbonate, CaCO s , occurs in nature in great abund- 
ance ; it is found as dolomite ; as limestone, which, when granu- 
lar and crystalline, is called marble ; as calcite, which, when pure 
and crystalline, is known as Iceland spar and is used for making 
lenses for optical instruments. It is found, also, as oyster shells, 
coral, &gg shells and chalk. 

The precipitated carbonate of calcium, used in medicine, is 
formed by adding sodium carbonate to calcium chloride in solu- 
tion; it is a white, amorphous, insoluble powder. The car- 
bonate of calcium is insoluble in pure water, but soluble to 
some extent in water containing carbon dioxide, for this reason 
it often occurs dissolved in natural waters, and when these are 
boiled the carbon dioxide is expelled and the carbonate is pre- 
cipitated. The formation of stalactites, and of incrustations on 
the interior of boilers is due to the precipitation of calcium car- 
bonate following the expulsion of carbon dioxide. 

Calcium Sulphate, CaS0 4 , occurs in nature as gypsum, with 
two molecules of water of crystallization. It is prepared by 
adding sulphuric acid to a concentrated solution of calcium 
chloride, when it precipitates from solution; the precipitate is 
removed by filtration and dried. 

Properties. A white, nearly insoluble powder, one part 
requiring 400 to 500 parts of water for solution. By heating 
the naturally occurring salt to about no°, water is driven off 
and anhydrous calcium sulphate remains ; this compound, when 
ground to an impalpable powder, is known as " plaster of 
Paris." The " setting " of plaster of Paris is due to its chemical 
union with water. 

Calcium Nitrate, Ca(N0 3 ) 2 , is produced in nature by decay 
of nitrogenous organic matter in presence of lime. 



THE METALLIC ELEMENTS 177 

Preparation, By the action of diluted nitric acid on calcium 
carbonate, evaporating and crystallizing the solution. 

Properties. Colorless crystals, soluble in water. Used in 
making potassium nitrate. 

Calcium Phosphate, Tricalcium Phosphate, Ca 3 (P0 4 ) 2 . 
Occurs in nature in deposits in the earth as apatite ; also found 
in bones and teeth of animals. Can be made from bone ash by 
action of hydrochloric acid, which dissolves the salt ; it is then 
precipitated by adding ammonia water. 

Preparation. Prepared by adding Na 2 HP0 4 and ammonia 
water to solution CaCl 2 : 

2^a 2 HP0 4 + 3CaCl 2 + 2 NH 4 OH = Ca 3 (P0 4 ) 2 + 4NaCl + 2NH4CI 

+ 2H 2 0. 

Properties. Tasteless, amorphous, insoluble powder. 

Superphosphate, or Acid Phosphate of Calcium, CaH 4 - 
(P0 4 ) 2 . Made by digesting the tricalcium phosphate with 
sulphuric acid, and occurs as a soluble deliquescent salt. Its for- 
mation is shown by the equation : 

Ca 8 (P04) 2 + 2H 2 S0 4 = 2CaS04 + CaH^PO.H 

This salt is present in certain " baking powders," and in an 
impure form with calcium sulphate in fertilizer. 

Bone Ash is formed by burning bones, and consists of the 
inorganic, non-volatile constituents of bones, chiefly tricalcium 
phosphate. 

Bone Black is bone charcoal, formed by destructive distilla- 
tion of bones, and contains carbon in addition to what is found 
in bone ash. 

Chlorinated Lime, Calcium Hypochlorite, Bleaching 
Powder {Chloride of Lime). Probably, Ca(C10) 2 .CaCl 2 . 
2H 2 0, a molecular compound of chloride and hypochlorite of 
calcium. 

Prepared by passing chlorine over dry calcium hydroxide at 
the ordinary temperature of the air : 

2Ca(OH) 2 + 2Cl 2 =rCa(C10) 2 .CaCl 2 + 2H 2 0. 
13 



I78 TEXT-BOOK OF CHEMISTRY 

Properties. A white, soluble, deliquescent powder, exhaling 
the odor of hypochlorous acid, and decomposed by exposure to 
air. It gives off chlorine when acted upon by acids, and should 
contain not less than 30 per cent, of available chlorine. 

Used largely as a bleaching and disinfecting agent, and for 
obtaining chlorine. 

Calcium Carbide, CaC 2 , is prepared by melting a mixture of powdered 
calcium oxide and coke-dust in an electric furnace. 

Properties. It occurs in dark-colored masses, having a metallic ap- 
pearance, and giving off the odor of acetylene by absorption of atmos- 
pheric. moisture. It is used in preparation of acetylene for illuminating 
purposes, by the action of water, thus : 

CaG + 2H 2 = GH 2 + Ca(OH) 2 . 

Tests for Calcium. 

1. Solutions of calcium salts give a white precipitate with the 
carbonates of potassium, sodium (or ammonium). 

2. Sodium phosphate gives a white precipitate in neutral 
solutions. 

3. Ammonium oxalate gives a white precipitate, insoluble in 
acetic, soluble in hydrochloric acid. 

4. Sulphates in strong solution give a white precipitate. 

5. A reddish-yellow color is imparted to the flame. Ammo- 
nia water gives no precipitate. 

STRONTIUM. 

Symbol, Sr. Atomic Weight, 87. Valence, II. 

History. Named for the village of Strontium, in Scotland, 
where a compound of the metal was first detected. The metal 
was separated by Sir Humphrey Davy in 1808. 

Occurrence in Nature as the carbonate in strontianite, and 
as sulphate in celestite. Found frequently with calcium. 

Preparation. By electrolysis of the fused chloride. 

Properties. A yellow, ductile metal; specific gravity, 2.5. 



THE METALLIC ELEMENTS 1 79 

It decomposes water, oxidizes in the air, and burns with a bright 
light when heated, imparting a red color to the flame. 

Strontium compounds are like those of calcium, except that 
they are more basic in character and properties. 

Strontium Oxide is obtained by heating the nitrate, and is 
like calcium oxide in properties. The Hydroxide is more solu- 
ble in water than the corresponding salt of calcium. 

The Strontium Bromide, SrBr 2 , and Strontium Iodide, Srl 2 , 
are both official. These salts, as well as the nitrate and chloride, 
may be obtained by dissolving the carbonate in the respective 
acids and crystallizing. They are white, soluble compounds. 

Strontium nitrate is largely used in pyrotechnics to form 
" red fires." 

Tests for Strontium. 

1. Solutions of strontium compounds with solutions of carbo- 
nates, oxalates, and phosphates, give a white precipitate. 

2. Sulphates give a white precipitate. 

3. Potassium chromate gives a pale-yellow precipitate, soluble 
in acetic and hydrochloric acid. 

4. Potassium dichromate gives no precipitate ; differing from 

barium. 

BARIUM. 

Symbol, Ba. Atomic Weight, 136. Valence, II. 
Occurrence in Nature in large masses, as heavy spar, or 
barium sulphate, and as witherite, or barium carbonate. Com- 
pounds of barium are distinguished by their high specific 
gravity. The basic properties of barium are more strongly de- 
veloped than they are in calcium or strontium. The salts of 
barium can be prepared from the carbonate by the action of the 
appropriate acid. The sulphate of barium is sometimes em- 
ployed for preparation of other salts. This is done by first 
heating with carbon to form the sulphide, and then dissolving 
the sulphide in the appropriate acid. 



l80 TEXT-BOOK OF CHEMISTRY 

Preparation. By electrolysis of the fused chloride. 

Properties. A bright, yellow metal; specific gravity 3.6; 
rapidly oxidizes in the air ; decomposes water like sodium. 

Barium Chloride, BaCl 2 , is of interest because it is largely 
used as a reagent to precipitate the soluble sulphates from solu- 
tion. It is prepared by dissolving barium carbonate in diluted 
hydrochloric acid, evaporating and crystallizing. 

Properties. Clear, colorless crystals, containing two mole- 
cules of water of crystallization; permanent in the air; soluble 
in water ; poisonous, like all soluble salts of barium. 

Barium Oxide, BaO, is prepared by heating the nitrate. It 
is a grayish-white, amorphous mass ; specific gravity 5.5 ; 
fusible in the oxyhydrogen flame ; unites with water with evolu- 
tion of heat to form the hydroxide. 

Barium Dioxide, Ba0 2 , is prepared by heating the oxide to 
dull redness in air or oxygen. When heated to a still higher 
temperature it gives up oxygen and again becomes the monox- 
ide; on account of this property, it has been employed in the 
manufacture of oxygen, but the power of the oxide to absorb 
and give up oxygen disappears after a time. 

Properties. Barium dioxide is a grayish-white solid, 
slightly soluble in water, forming the hydroxide; it is used 
for making hydrogen dioxide by adding water and a mineral 
acid, as shown in the equations : 

Ba0 2 + 2HCI = H 2 2 + BaCl 2 . 
Ba0 2 + H 2 + C0 2 = H 2 2 + BaC0 3 . 

Barium Hydroxide, Ba(OH) 2 , is prepared by slaking the 
oxide, or by precipitating a strong solution of barium salt by 
sodium or potassium hydroxide. 

Properties. An amorphous, white powder; soluble in 20 
parts of water; the solution in water gives a strongly alkaline 
liquid, known as baryta water. At a red heat the hydroxide 



THE METALLIC ELEMENTS 151 

fuses and solidifies to a crystalline mass on cooling, like caustic 
potash. 

The other salts of barium are made by dissolving the carbo- 
nate in the respective acids, and are like the corresponding cal- 
cium salts in properties. The sulphate is insoluble in water and- 
acids. 

Toxicology. The soluble salts of barium act as poisons, producing 
vomiting, diarrhoea, albuminuria, haematuria and convulsions preceding 
death. The antidote is a weak solution of sulphuric acid, or other suit- 
able sulphate, in order to form the insoluble barium sulphate. 

Tests for Barium. 

1. Carbonates, phosphates or oxalates of alkalies give white 
precipitate. 

2. Sulphuric acid or sulphates give white precipitate in- 
soluble in dilute acids. 

3. Potassium chromate and dichromate give a pale yellow 
precipitate soluble in HC1. 

4. Compounds color the flame pale yellowish-green. 

Radium. This element, which has not as yet been obtained in the 
free state, is best known in the form of its bromide or chloride, and the 
name radium is commonly applied to these salts. The element belongs 
to the group of the alkaline earth metals, and it stands next to thorium 
in MendelejefFs system of classification. As determined by Madam 
Curie, it has the atomic weight of 225. 

Radium is obtained from the mineral pitchblende, and it is associated 
in this mineral with uranium, polonium, actinium and thorium. Radium 
chloride is prepared from the residue of pitchblende, after the separa- 
tion of uranium salts, by repeated crystallization upon treating with 
hydrochloric acid. The rarity and consequent high price of the salt is 
due to the immense amount of labor involved in its preparation. 

The salts of the elements uranium, thorium, polonium, actinium and 
radium emit a form of energy which has the power to affect the photo- 
graphic plate, and is luminous in the dark. Investigations point to the 
conclusion that there are both visible and invisible emanations from 
these, so-called, radio-active bodies; the fluorescent, or visible rays, 
being accompanied by invisible forms of energy, the latter having been 
referred to as " dark light." The property of fluorescence first called 



1 82 TEXT-BOOK OF CHEMISTRY 

attention to these qualities, and the power of pitchblende to affect the 
photographic plate in the dark led to the investigations which resulted 
in the discovery of radium. 

The opinion of scientists inclines to the belief that the emanations 
from radium are, at least in part, of a material character, and that they 
are of three kinds : ( i ) Real atoms, much larger than the free electrons, 
and positively electrified. These are easily checked in passing through 
obstructions, they cause air to become a conductor and they act on the 
photographic plate. (2) Free electrons, or matter identical with the 
cathode stream in the ultra-gaseous state. (3) Rays having high power 
of penetration, and believed by some to be like the Roentgen rays. 

In giving expression to the degree of radio-activity of radium, the 
standard, or unit of comparison, is the amount of activity in metallic 
uranium, taken as one. It is claimed that an activity of over one and 
three quarter millions has been obtained for radium. 

Radium is luminous in the dark, its temperature is above that of the 
surrounding air, and it is capable of melting its own weight of ice 
every hour. When kept near the skin in a glass tube for some time 
it causes painful ulceration which is slow to heal. Animal and bacterial 
life continuously exposed to its rays are weakened or destroyed. 



THE METALLIC ELEMENTS 



183 



Analytical Reactions. 
Directions for analysis of an aqueous solution containing one 
or all of the metallic elements hitherto considered. 



To the solution add NH 4 C1, NH 4 OH, (NHJ 2 CCX 
filter. 



boil and 



Precipitate. 


Filtrate. 


Ba, Ca, Sr. 


Mg, NH 4 , Na, K, Li. 


Wash, dissolve in acetic acid, add 




K 2 Cr 2 7 , and filter. 


Add (NH 4 ) 2 HP0 4 and filter. 


Ppt. 


Filtrate. 


Precipitate. 


Filtrate. 


Ba, 


Ca, Sr. 


Mg, as 


NH 4 , Na, K. 


Yellow. 


Neutralize with am- 


MgNH 4 HP0 4 . 


Evaporate to dryness, 




monia water and add 




ignite, test dry residue for 




K 2 Cr0 4 




sodium and lithium by flame 
test on platinum wire. 




Ppt. 

Sr, 


Filtrate. 




Dissolve residue in water 




Ca. 




and test for potassium by 




Pale 


Add ammon. 




PtCl 4 . 




yellow. 


oxalate : Ca 
ppts. white as 
oxalate. 




Test original solution for 
ammonium. 



In the above analysis the addition of ammonium chloride 
serves to retain the magnesium salts in solution, the ammonium 
hydroxide to neutralize any acid which might be present, the 
ammonium carbonate serving as the essential precipitating 
agent. 



184 TEXT-BOOK OF CHEMISTRY 

THE EARTH METALS. 

Aluminum, Cerium and a Number of Rare Metals. 

ALUMINUM. 

Symbol, Al. Atomic Weight, 27. Valence, III. 

Occurrence in Nature. One of the most widely distri- 
buted elements in nature. Generally found in the solid mineral 
portion of the earth; hardly ever in the vegetable or animal 
kingdoms. Found as the oxide crystallized in ruby, sapphire 
and corundum more or less colored by other substances; also 
as silicate in clay, mica, slate, granite and in silicated rocks. 

Preparation. By heating the chloride with sodium. Alumi- 
num is extensively prepared by electrolysis of the double fluoride 
of aluminum and sodium, to which aluminum oxide is added 
as the operation proceeds. 

Properties. A silver-white metal, very ductile and mallea- 
ble; specific gravity, 2.67, a light metal; fuses at a red heat, 
but will not volatilize ; not affected by dry air, burns when thin 
sheets are heated in oxygen. Nitric or sulphuric acid will not 
affect aluminum in the cold ; it is dissolved, however, by hydro- 
chloric acid. It dissolves in potassium or sodium hydroxide 
solution. 

Aluminum is capable of taking a high polish, and this, with 
its property of permanence in the air, fit it for use^in making 
ornamental articles and vessels. It is also used in making 
scientific instruments. Aluminum bronze contains ten per cent, 
of aluminum and ninety per cent, of copper. Aluminum is a 
trivalent element, but two atoms usually go together exerting 
the quantivalence of six. 

Aluminum Chloride, A1 2 C1 6 , may be prepared in solution by 
dissolving aluminum in hydrochloric acid, from which it crys- 
tallizes with six molecules of water. If this salt be heated with 






THE METALLIC ELEMENTS 1 85 

the view of obtaining the anhydrous chloride it is decomposed 
into hydrochloric acid and aluminum oxide. To prepare the 
anhydrous chloride, heat a mixture of aluminum oxide and 
carbon and pass chlorine over this. The simultaneous action 
of carbon and chlorine on the A1 2 3 results in the formation 
of the chloride. 

A1 2 3 + 3C + 3C1 2 = 3CO + A1 2 C1 6 . 

The chloride can also be formed by the action of chlorine on 
the heated metal. In properties aluminum chloride is a de- 
liquescent, soluble, crystalline solid. The anhydrous salt is 
used in making metallic aluminum. 

Aluminum Oxide, A1 2 3 . Found in nature crystallized with 
coloring matter, as ruby, sapphire, and impure as emery. 

Prepared by heating the hydroxide : 

Al 2 (OH) 6 = Al 2 3 + 3H 2 0. 

Properties. A white, amorphous, insoluble powder ; fuses to 
a transparent mass in the oxyhydrogen flame. To render it 
soluble for analysis is fused with caustic alkalies. 

Aluminum Hydroxide, Al 2 (OH) 6 . Prepared by adding 
ammonia water to solution of aluminum salt, or by adding a 
solution of alkaline carbonate to the same : 

Al 2 (S0 4 )3 + 6NH 4 OH = Al 2 (OH) 6 + 3(NH 4 ) 2 SO i , r A1 2 (S0 4 ) 3 + 

3Na 2 C0 3 + 3H 2 = Al 2 (OH)« + 3Na 2 S0 4 + 3CXX 

Explanation of formation of hydroxide instead of carbonate 
by above reaction is found in the fact that aluminum is too feeble 
a base to combine with this weak acid. 

Properties. A white gelatinous precipitate. When fresh, 
soluble in acids and alkalies ; when washed and dried, nearly in- 
soluble in acids, and a white powder. 

Aluminum hydrate is used in the process of dyeing to fix the 
coloring matter to the fabric of cloth; it has an affinity for 



I 86 TEXT-BOOK OF CHEMISTRY 

organic and inorganic coloring matter, and also an affinity for 
the organic material of which cloth is manufactured ; on account 
of these properties it fixes the dye, and such action is known 
as that of a mordant — {Mordeo, to bite). 

Aluminum hydroxide shows a feebly acidic tendency when 
brought in the presence of powerful alkalies like sodium and 
potassium ; with potassium it forms an aluminate, in which the 
metal takes the part of an acid radical, as shown by the formula, 
KAIO3, potassium aluminate. 

Aluminum Sulphate, A1 2 (S0 4 ) 3 . Prepared by dissolving 
the hydroxide in sulphuric acid, or by digesting sulphuric acid 
with clay and evaporating the solution. 

Properties. A white, crystalline powder; soluble in water. 

It has power to combine with sulphates of alkalies to form 

double salts, thus : 

K 2 S0 4 .Al 2 (SO4)3.2 4 H 2 0. 

Alums. A general term applied to salts consisting of a mole- 
cule of the sulphate of a univalent element, with a molecule of 
the sulphate of a trivalent element, and twenty-four molecules 
water of crystallization : 

KoSCXAUCSO^^HoO, Potassium Aluminum Alum. 

(NH^SCXALCSOOs^HzO, Ammonium Aluminum Alum. 

K 2 S04.Cr 2 (S04)3.24H 2 0, Potassium Chromium Alum. 

(NH 4 ) 2 S04.Fe 2 (S04)3.24H 2 0, Ammonium Iron Alum. 

Official Alum, K 2 S0 4 .A1 2 (S0 4 ) 3 .2 4 H 2 0. 

This salt is prepared by making a solution of aluminum sul- 
phate, as described above, mixing this with a solution of potass- 
ium sulphate and evaporating the liquid for the formation of 
cystals. 

Properties. Large, eight-sided, colorless crystals; sweetish, 
astringent taste; acid reaction. Soluble in nine parts water, 
0.3 parts boiling water. The crystals, when exposed to the 
air, will absorb ammonia and their surfaces become white. 



THE METALLIC ELEMENTS ' 1 87 

Dried Alum, Alumen Exsiccatum, Burnt Alum-. Alum from 
which water of crystallization has been expelled by heat. A 
white powder, soluble in hot water ; slowly soluble in cold water. 

Aluminum Silicates. These are found in nature with po- 
tassium and sodium, as felspar; and as mica and granite, with 
calcium. A gradual disintegration of these minerals results in 
removal of the sodium and potassium to the soil, the insoluble 
silicates being left behind, with water, constituting clay. These 
compounds are usually colored by iron salts. Pure clay, free 
from iron salts, is called kaolin, or porcelain clay. Earthenware 
is made by moulding clay, and heating to expel water. 

Porcelain is made of kaolin mixed with felspar, or potas- 
sium aluminum silicates, which when heated, furnish the glaze. 
Glass is the silicate of calcium and sodium, crown glass ; or of 
calcium and potassium, Bohemian glass ; or of potassium and 
lead, flint glass. Crown glass, the silicate of calcium and sodium, 
is the ordinary window-glass, it has a greenish tinge due to the 
presence of small amounts of iron salts. Bohemian, or potash 
calcium glass, is very infusible, and resistant to the action of 
acids and alkalies, and for these reasons it is largely used in the 
laboratory. Flint glass, potassium lead silicate, is remarkable 
for its density, lustre, and refractive power. It is the most 
fusible and readily attacked by chemicals. 

Ultramarine (Lapis Lazuli). This was formerly obtained solely as a 
valuable mineral, but is now made by artificial means. Its exact com- 
position is not known, but it contains aluminum and sodium silicate, and 
sodium polysulphides. Made by heating together sodium carbonate, 
sodium sulphate, clay, carbon and sulphur. 

Tests for Aluminum. 
1. Sodium, or potassium hydroxide gives a gelatinous pre- 
cipitate of aluminum hydroxide, soluble in excess. Ammonia 
water gives the same precipitate, insoluble in excess. 



1 88 TEXT-BOOK OF CHEMISTRY 

2. Sodium, or potassium, carbonate gives a precipitate of 
aluminum hydroxide, with escape of carbon dioxide. 

3. Ammonium sulphide gives same precipitate as in 2, with 
escape of H 2 S : 

Al,(SO«). + 3(NH*) 2 S -f 6H 2 = Al 2 (OH) 6 + 3(NH 4 ) 2 S0 4 + 3H 2 S. 

4. Sodium phosphate gives white precipitate, soluble in acids 
except acetic. 

Cerium, Ce=i39. Occurrence as silicate in cerite; not 
abundant. Salts resemble those of aluminum. Ammonium 
oxalate forms a precipitate of cerium, oxalate with solutions of 
cerium. 

The oxalate is a white, insoluble, granular powder, given 
internally for nausea. Salts of cerium heated to redness and 
residue of oxide dissolved in sulphuric acid, gives a blue color 
with a crystal of strychnine, which turns purple and then red. 

Cerium salts precipitate the hydroxide on adding (NH 4 ) 2 S, 
NH 4 OH, or NaOH, like aluminum. 

METALS OF THE IRON GROUP. 

The metals, iron, cobalt, nickel, manganese, chromium and 
zinc, form sulphides (except chromium) which are insoluble in 
water but soluble in dilute acids, and are precipitated from solu- 
tion by ammonium sulphide. Their oxides, hydroxides, car- 
bonates, phosphates and sulphides are insoluble. 

These metals decompose water at a red heat and dissolve 
readily in dilute sulphuric or hydrochloric acid, replacing the 
hydrogen. 

Many of them form both basic and acid oxides, showing the 
properties of metals, on the one hand, and of non-metals on the 
other. In the compounds in which they enter as bases most of 
them are bivalent in one class of salts, and apparently trivalent 
but probably quadrivalent in another, thus : 



THE METALLIC ELEMENTS 1 89 



CI 
MnCL, or Mn< Mn 2 Cl 6 or 

X C1 



\ 



CI 

r-Cl 

CI 

CI 

Mn^-Cl 
X C1 

Manganous chloride Manganic chloride 



In some other compounds they are sexivalent. Zinc is bi- 
valent usually. 

IRON (Ferrum). 

Symbol, Fe. Atomic Weight, 55. Valence, II., IV., and VI. 

History. Known to the ancient Egyptians and Assyrians. 
First employed as malleable iron, made by smelting ores with 
charcoal. Steel was described by Homer, and known to the 
ancient Greeks; the Chalybes, who lived on the shores of the 
Black Sea, were engaged in its manufacture. 

Occurrence in Nature. Iron occurs native in meteorites, 
which consist chiefly of metallic iron with some nickel. The 
metal is usually found in combination, and is widely distributed 
in the soil as the oxide, imparting a reddish-brown color. It 
occurs as ferric oxide, or haematite, Fe 2 3 ; ferrous ferric 
oxide, or magnetic iron ore, FeO.Fe 2 3 ; ferrous carbonate, 
or spathic iron ore, FeCO s ; ferric sulphide, or iron pyrites, 
FeS 2 . Iron occurs in plants in the chlorophyll, and in animals 
in the haemoglobin. It is found in chalybeate mineral waters 
as ferrous sulphate and carbonate. 

Preparation. By heating the oxides or carbonate with coke 
and limestone in large conical furnaces, at the base of which a 
blast of hot air is forced in. The iron ore and coke are fed into 
the furnace from the top in alternating layers, and by incom- 
plete combustion in a layer of coke carbon monoxide is formed, 
this coming in contact with the iron ore removes oxygen and 
liberates the metal, forming carbon dioxide. The dioxide 
reaching another layer of heated coke again forms carbon mon- 
oxide, and a repetition of these changes continues to the top 



I9O TEXT-BOOK OF CHEMISTRY 

of the furnace. The limestone with silicon of the ore forms 
slag, or silicate of calcium, which serves to protect the liberated 
metal. Molten iron and slag separate at the base of the fur- 
nace by a difference in specific gravity, iron being drawn off 
at the lower level. 

Iron formed in this way is known as pig, or cast iron, and 
contains from 3 to 6 per cent, of carbon, besides some silicon and 
phosphorus ; sometimes small percentages of other metals. 

Wrought Iron, the purest commercial form, contains from 
.2 to .6 per cent, of carbon — official as iron wire. 

Steel, intermediate in composition between the two varieties, 
contains .16 to 2 per cent, of carbon. 

Carbon is removed from the cast iron by heating in an oxidiz- 
ing flame. Steel can be made from cast iron by partial removal 
of carbon, or by mixing cast iron and wrought iron in proper 
proportions. 

Properties. A gray metal, hard and tenacious. When 
heated it becomes soft, malleable and ductile, melting at 1150 
to 1500 . Specific gravity about j.j. 

Iron is not much affected by dry air but easily oxidized when 
moisture is present. It forms two series of salts, ferrous and 
ferric, being bivalent in the former, and apparently trivalent in 
the latter. Compounds in which iron acts like a non-metal are 
known in the form of ferrates, where the metal is sexivalent. 

Ferrum Reductum, Reduced Iron, Iron by hydrogen. A 
preparation of metallic iron in a fine state of subdivision. 

Prepared by passing dry hydrogen gas over heated ferric 

oxide : 

Fe 2 3 + 3H2 = 3H2O + Fe 2 . 

Properties. A fine, dark-gray powder; odorless, insoluble 
in water ; containing not less than 90 per cent, of metallic iron. 
It is easily oxidized by exposure. Used in medicine in form 
of pills. 



THE METALLIC ELEMENTS I9I 

Halogen Salts of Iron. 
Ferrous Chloride, Protochloride of iron, FeCl 2 .. Made by 
dissolving iron in hydrochloric acid, and may be crystallized 
from this solution in green, deliquescent prisms. 

Fe + 2HCI = FeCl 2 + H 2 . 

Ferric Chloride, Sesqui-chloride, or perchloride of iron, 
Fe 2 Cl 6 .i2H 2 0. Prepared by boiling a solution of ferrous 
chloride with hydrochloric and nitric acids : 

6FeCl 2 + 2HNO3 + 6HC1 = 3Fe 2 Cl 6 + 4H2O + 2NO. 

By evaporating the solution crystals may be obtained. 

Properties. Orange-yellow, crystalline masses ; deliquescent ; 
soluble in water and in alcohol; acid reaction; styptic taste. 
Aqueous solution containing 29 per cent, of the anhydrous 
salt, is the official Liquor Ferri Chloridi. The tincture of 
chloride of iron, made by adding 35 parts of the above solution 
to 65 parts of alcohol, and allowed to stand for three months ; 
the iron is thus partly reduced to ferrous state. 

Ferrous Iodide, Fel 2 . Prepared by warming a mixture of 
iodine, iron filings and water. Easily oxidized with liberation 
of iodine. The solution mixed with sugar of milk, and evapor- 
ated to dryness, constitutes saccharated iodide of iron. Syrup 
of iodide of iron is a solution of ferrous iodide and sugar. 
Ferric iodide does not exist at ordinary temperature of air. 

Ferrous Bromide, FeBr 2 . Prepared like ferrous iodide. 

Occurs in bluish-green crystalline tablets, with 6H 2 0. Ferric 

Bromide, Fe 2 Br 6 , obtained in dark-red crystals by direct union 

of the elements. 

Iron Sulphur Compounds. 

Ferrous Sulphide, FeS. Made by fusing together sulphur 
and iron. Occurs in dark-gray masses, metallic appearance ; in- 
soluble in water, soluble in acids with escape of H 2 S. Largely 
used for making hydrogen sulphide as a reagent. 



I92 TEXT-BOOK OF CHEMISTRY 

Ferric Sulphide, FeS 2 . Occurs in nature as iron pyrites, 
and is largely used for making sulphuric acid and ferrous sul- 
phate by roasting. 

Oxygen Salts of Iron. 

Ferrous Oxide, FeO, may be obtained by reducing the ferric 
oxide by the action of carbon monoxide, or hydrogen, but it is 
very unstable and rapidly absorbs oxygen from the air. 

Ferrous Hydroxide, Fe(OH) 2 , is formed by adding an 
alkaline hydroxide to a ferrous salt. It is a greenish-white 
powder, and rapidly absorbs oxygen to form brown ferric 
hydroxide : 

FeSO* + 2NH4OH = Fe(OH) 2 + (NH 4 ) 2 S0 4 . 
2Fe(OH) 2 + O + H 2 = Fe 2 (OH) 6 . 

Ferric Oxide, Fe 2 O s . Occurs in nature as haematite. Pre- 
pared by heating ferric hydroxide to expel water : 

Fe 2 (OH) 6 = Fe 2 3 + 3H 2 0. 

Properties. A reddish-brown powder, used in the arts for 
polishing and as a pigment. A feeble base. 

Ferric Hydroxide, Ferric Hydrate, Hydrated oxide of 
iron, per- or sesqui-oxide of iron, red oxide of iron, Fe 2 (OH) 6 . 

Prepared by adding ammonia water to solution of ferric salt 
as a reddish-brown, gelatinous precipitate : 

Fe 2 (S0 4 ) 3 + 6NH.OH = Fe 2 (OH) 6 + 3(NH 4 ) 2 S0 4 . 

Properties. A reddish-brown, insoluble powder. When 
freshly precipitated, used as an antidote in arsenic poisoning. 
Hydrated oxide of iron is used for this purpose, and is extem- 
poraneously prepared by adding milk of magnesia to solution 
of ferric sulphate. 

Ferrous-ferric Oxide, FeO.Fe 2 O s , occurs in nature as mag- 
netic iron ore, or loadstone. It is formed when iron is burned 
in oxygen, or when steam is passed over red-hot iron. In 



THE METALLIC ELEMENTS 193 

properties, it is a black solid, of metallic lustre, possessing 
magnetic power. 

Ferrates. When potassium nitrate is fused with iron filings, 
a red mass containing potassium ferrate, K 2 Fe0 4 , is formed, in 
which iron takes the part of a non-metal. The acid, H 2 Fe0 4 , 
has not been separated, nor has the anhydride, FeO s , iron 
trioxide. Iron has the valence of six in this compound. 

Ferrous Sulphate, Copperas, Green vitriol, FeS0 4 -7H 2 0. 

Prepared by dissolving iron in dilute sulphuric acid and crys- 
tallizing : 

Fe + H 2 S0 4 = FeS0 4 + H 2 , 

or by carefully roasting the native sulphide : 

FeS 2 + 3O2 = FeS0 4 + S0 2 . 

Properties. Large, bluish-green, prismatic crystals ; efflo- 
rescent and absorbing oxygen to form some ferric sulphate 
when exposed to air ; soluble in water, insoluble in alcohol. The 
dried ferrous sulphate formed as a white powder by heating 
carefully to ioo° to expel four molecules of water. Granu- 
lated ferrous sulphate is formed as a granular powder by adding 
alcohol to aqueous solution of ferrous sulphate and drying the 
precipitate. 

Ferric Sulphate, Fe 2 (S0 4 ) 3 . Prepared by boiling a solu- 
tion of ferrous sulphate with sulphuric and nitric acids : 

6FeS0 4 + 3H 2 S0 4 + 2HNO3 = Fe 2 ( S0 4 ) 3 + 4H2O + 2NO. 

The solution is known as Solution of Persulphate of Iron, 
Solution of Ferric Sulphate; a reddish-brown liquid. By 
evaporating the liquid the salt may be obtained as a white mass. 
Forms alums with alkali sulphates. Iron Ammonium Alum, 
a pale, violet-colored, soluble salt. 

Solution of Ferric Subsulphate, M ousel's Solution. 

Prepared like the above salt except that the amount of sul- 
phuric acid used is insufficient to form the normal salt. 
14 



194 TEXT-BOOK OF CHEMISTRY 

Properties. A red liquid, miscible with water and alcohol, 
and powerfully astringent. (It is said to have the composi- 
tion, Fe 2 (S0 4 ) 3 -5Fe 2 3 .H 2 0.) 

Ferrous Carbonate, FeCO s . Occurs in nature as spathic 
iron ore. 

Prepared by adding sodium carbonate to solution of ferrous 

sulphate : 

FeS0 4 + Na 2 C0 3 = FeC0 3 + Na 2 S0 4 . 

The carbonate precipitates as a white powder, which rapidly 
turns dark by oxidation to ferric hydroxide. It is insoluble in 
water, slightly soluble in water containing C0 2 . This salt, 
mixed with sugar to prevent oxidation, is used as sac char at ed 
carbonate of iron. Ferric carbonate is not known. 

Ferric Nitrate, Fe 2 (N0 3 ) 6 . Formed by dissolving iron in 
nitric acid. It forms colorless, deliquescent, soluble, cubical 
crystals. A six per cent, solution is official. Ferrous nitrate is 
not known. 

Ferrous Phosphate, Fe 3 (P0 4 ) 2 .8H 2 0. Occurs in nature 
in the blue mineral vivianite. 

Obtained as a precipitate by the action of sodium phosphate 
on ferrous sulphate, in presence of sodium acetate. 

Properties. A slate-colored powder, turning dark by ab- 
sorption of oxygen : 

3FeS0 4 + 2Na 2 HP0 4 = Fe 3 (P0 4 ) 2 + 2Na 2 S0 4 + H 2 S0 4 . 

Ferric Phosphate, Fe 2 (P0 4 ) 2 , may be obtained as a white 
precipitate by adding sodium phosphate to solution of ferric 
chloride. 

2Na 2 HP0 4 + Fe 2 Cl 6 = Fe 2 (P0 4 ) 2 + 4NaCl + 2HCI. 

Ferric Hypophosphite, Fe 2 (H 2 P0 2 ) 6 . Prepared by dis- 
solving ferric hydroxide in hypophosphorous acid, and crystal- 
lizing. A grayish powder, nearly insoluble in water. 

Dialyzed Iron is prepared by adding ammonia water to solu- 



THE METALLIC ELEMENTS 195 

tion of ferric chloride as long as the precipitate formed is redis- 
solved on shaking, and placing the mixture in a dialyzer upon 
water. The water is renewed from time to time until all ammo- 
nium chloride passes out. 

Properties. A dark, reddish-brown, odorless liquid, without 
the styptic taste and astringent properties of other iron com- 
pounds. Contains about five per cent, of ferric hydroxide and 
some ferric chloride. Is easily coagulated by acids, alkalies, 
and some salts. 

Tests for Iron. 

1. Ferrous compounds are converted into ferric by heating 
with nitric acid, and this is necessary for their complete precipi- 
tation. 

2. Iron salts are precipitated black by ammonium sulphide. 

3. Alkaline hydroxides give with ferrous salts a white pre- 
cipitate, soon turning dark ; with ferric salts, a reddish-brown 
gelatinous precipitate. 

4. Alkaline carbonates give with ferrous salts a white precipi- 
tate, soon turning dark ; with ferric salts, a reddish-brown pre- 
cipitate and escape of C0 2 . 

5. Potassium ferrocyanide gives with ferrous salts a light- 
colored precipitate, soon turning light-blue; with ferric salts a 
dark-blue precipitate. (Prussian blue, Fe 4 3Fe(CN) 6 .) 

6. Potassium ferricyanide gives with ferrous salts a deep- 
blue precipitate (Turnbull's blue, Fe 3 2Fe(CN) 6 ) ; with ferric 
salts an olive green, or greenish-brown coloration, and no pre- 
cipitate. 

7. Potassium sulphocyanate gives with pure ferrous salts no 
change; with ferric salts a deep-red color. 

8. Tannic acid gives no precipitate with a pure ferrous salt ; 
with ferric salts it gives a greenish-black precipitate. 

MANGANESE. 
Symbol, Mn. Atomic Weight, 55. Valence, II. and IV. 
Occurrence in Nature. As black oxide or pyrolusite, 



I96 TEXT-BOOK OF CHEMISTRY 

Mn0 2 ; and as sesquioxide, Mn 2 O s . In small quantities with 
other minerals. 

Preparation. By heating the carbonate, or the above oxides 
with charcoal (C). 

Properties. It resembles iron in its properties ; is darker in 
color, harder and more easily oxidized ; sp. gr. 7.2 ; decom- 
poses boiling water. It forms both basic and acid oxides, with 
their corresponding salts. 

Basic Oxides. The basic oxides of manganese form two 
classes of manganese salts with acids, i. e., manganous com- 
pounds, in which the metal is bivalent and strongly basic ; and 
manganic compounds, in which the metal is apparently triva- 
lent, but is really quadrivalent, like iron, and feebly basic. 
These basic oxides are: 

Manganous Oxide, MnO. 

Manganous-Manganic Oxide, MnO.Mn 2 3 . 

Manganic Oxide, Mn 2 3 . 

Manganese Dioxide, MnO?. 

Manganous Oxide. MnO. 

Prepared by heating the carbonate. 

Properties. A greenish-gray insoluble powder, strongly basic, form- 
ing salts with acids, which usually have a delicate rose color. 

Manganic Oxide, Mn 2 3 . Prepared by heating the above oxide in a 
current of oxygen gas. 

Properties. A black insoluble powder. 

Manganese Dioxide, Binoxide of Manganese, Black Oxide 
of Manganese, Mn0 2 . Most important compound of man- 
ganese. 

Occurs in nature as pyrolusite. 

May be prepared by heating the nitrate. 

Properties. A dark grayish-black, metallic-looking mineral, 
of crystalline structure. It gives up oxygen when heated. It 
is used for preparation of chlorine and oxygen, and also in 
medicine. 



THE METALLIC ELEMENTS * 1 97 

Manganous Sulphate, MnS0 4 . 

Prepared by dissolving the dioxide in sulphuric acid, 

Mn0 2 + H 2 S0 4 = MnSO* + H 2 + O, 

evaporating to dryness and igniting the residue, to decompose any fer- 
rous sulphate that might be present, washing the residue with water, 
and crystallizing from the resulting solution. 

Properties. A pale rose-colored solid, isomorphous with the sulphate 
of zinc, deliquescent and soluble in water. 

Manganic Sulphate, Mn 2 (S04)3. 

Prepared by action of H 2 S0 4 on manganic oxide. 

Occurs as dark green powder. Solutions red color. Forms alums, 
K 2 S0 4 Mn 2 (S0 4 )3.2 4 H 2 0. 

Manganous Chloride, MnCl 2 . 

Prepared by dissolving manganese dioxide in hydrochloric acid, evap- 
orating to dryness and heating to dull redness, to decompose any iron 
salt present, washing the mass with water and crystallizing. 

Properties. Rose-colored, soluble, deliquescent crystals. 

Manganic Chloride, Mn 2 Cle, is made by dissolving manganic oxide in 
cold hydrochloric acid. Easily decomposed to dichloride by heat. 
Never been separated pure. 

The acid oxides of manganese are not known in the sepa- 
rate state, but only in combination. 

Manganic Anhydride, MnO s + H 2 = H 2 Mn0 4 , or man- 
ganic acid. 

Permanganic Anhydride, Mn 2 7 + H 2 = H 2 Mn 2 8 = 
2HMn0 4 , or Permanganic acid. 

Permanganic Acid, HMn0 4 , can be obtained in solution by 
electrolysis of a solution of potassium permanganate. 

Potassium Manganate, K 2 Mn0 4 . 

Prepared by heating together manganese dioxide, potassium 
carbonate and potassium chlorate. The manganese is con- 
verted into manganic acid, which combines with the potassium 
present : 

3Mn0 2 + 3 K 2 C0 3 + KC10 3 = zKMnO* + KC1 + 3C0 2 . 

The manganate may be washed out and crystallized as a 
green soluble salt. 



I98 TEXT-BOOK OF CHEMISTRY 

Potassium Permanganate, KMn0 4 . Prepared by dis- 
solving the manganate in acidulated water (or much water), 
when it is obtained as a violet-colored solution, with precipita- 
tion of manganese dioxide : 

3 K 2 Mn0 4 + 2ILSO4 = Mn0 2 + 2K 2 S0 4 + 2KM11O4 + 2H 2 0. 

Properties. From the solution it may be crystallized in 
slender prismatic crystals of dark purple color, soluble in water. 
It is a strong oxidizing agent. It is used largely in medicine 
as a disinfectant. 

Tests for Manganese. 

1. Ammonium Sulphide gives a pink precipitate, soluble in 
acetic and mineral acids. 

2. Ammonium, or Sodium Hydroxide gives a white precipi- 
tate which darkens by absorption of oxygen. 

3. Potassium, or Sodium Carbonate gives a white precipi- 
tate. 

4. Manganese Compounds heated on platinum foil with 
potassium carbonate and chlorate give a bluish-green mass, 
which, when dissolved in acidulated water, forms a violet- 
colored solution. 

5. Violet color is imparted to the borax bead. 

CHROMIUM. 

Symbol, Cr. Atomic Weight, 52. Valence, II. and IV. 

Occurrence in Nature. As chromite, or chrome iron ore, 
FeOCr 2 O s , which is similar in chemical structure to magnetic 
iron ore. The name signifies color, on account of the beauti- 
fully-colored compounds. 

Preparation. By heating the oxide with charcoal to a high 
temperature. 

Properties. Gray, metallic, crystalline powder; sp. gr. 
6.8; very hard. Chromium forms both basic and acid oxides, 



THE METALLIC ELEMENTS . 1 99 

and three series of salts, i. e., chromous and chromic com- 
pounds, in which chromium takes the part of a base, and the 
salts of chromic acid, in which chromium exhibits acid prop- 
erties. 

The basic oxides: 

Chromous oxide, CrO. 

Chromic oxide, Cr 2 3 . 

Chromous Oxide is not known in the anhydrous state. Is formed by 
adding potassium hydroxide to solution of chromous chloride — in the 
hydrated state Cr(OH) 2 — as a brown precipitate, which is rapidly oxi- 
dized in chromic oxide. It is a strong base. 

Chromic Oxide, Sesquioxide of Chromium, may be pre- 
pared by heating potassium dichromate with sulphur: 

K 2 Cr 2 7 + S = K 2 SC>4 + Cr 2 3 , . 

washing the resulting mass with water, when the oxide is left 
as a green powder, insoluble in water. It combines with acids 
to form salts, and is used in making green glass. It is known 
in commerce as chrome green. 

Chromic Hydroxide, Cr 2 (OH) 6 . 

Preparation. By adding solution of ammonium hydroxide 
to solution of chromic chloride, or other salt of chromium : 

Cr 2 Cl 8 + 6NH4OH = Cr 2 (OH) 6 + 6NH4CI. 

Properties. A bluish-green, gelatinous, insoluble powder. 
By dissolving the hydroxide in different acids, the salts of 
chromium are formed. 

Potassium chromium sulphate, and ammonium chromium 
sulphate are double salts having the chemical character of 
alums. 

The acid oxide of Chromium: 

Chromium Trioxide, Chromic Acid, Chromic Anhydride, 
CrO s . 

Preparation. By adding sulphuric acid to a concentrated 



200 TEXT-BOOK OF CHEMISTRY 

solution of potassium bichromate, the trioxide separates in 
needle-shaped crystals : 

K 2 Cr 2 7 + H 2 S0 4 = K 2 S0 4 + H 2 + 2Cr0 3 . 

Properties. Long, red, needle-shaped crystals; deliquescent 
when exposed to the air, and freely soluble in water. It is 
strongly corrosive, a powerful oxidizing agent, and when 
heated gives up oxygen. Its solution in water has acid prop- 
erties. 

The formation of chromic, and di-chromic acids may be ex- 
plained by the following equations : 

Cr0 3 + H 2 = HoCrO*, Chromic Acid. 
2Cr0 3 + H 2 = H 2 Cr 2 7 , Di-Chromic Acid. 

Chromic Acid, H 2 Cr0 4 ; made by adding water to CrO s and 
heating to ioo°, decanting, and clear liquid cooled to o°, when 
the acid separates in red, deliquescent crystals. 

Potassium Bichromate, Potassium Bichromate, K 2 Cr 2 7 . 
Preparation. By heating in an oxidizing furnace chrome iron 
ore and potassium carbonate. Chromic acid is thereby formed, 
which combines with the potassium, forming potassium 
chr ornate: 

2(FeOCr 2 3 ) + 4K 2 C0 3 + 70 = Fe 2 O s + 4C0 2 + 4K 2 Cr0 4 . 

The resulting mass is washed with water, which dissolves 
out the chromate. Potassium chromate, or yellow chr ornate 
of potash, can be crystallized from solution by evaporation; 
it is a yellow, crystalline solid, freely soluble in water. Upon 
acidifying the solution of potassium chromate with sulphuric 
acid and heating, potassium bichromate is formed : 

2K 2 Cr0 4 + H.SO* = K=S0 4 + H 2 + K 2 Cr 2 0r. 

Properties. Large, red crystals, soluble in ten parts water. 
When heated it fuses, and finally gives off oxygen. A strong 



THE METALLIC ELEMENTS ' 201 

oxidizing agent. By the action of alkalies it is converted into 
potassium chromate: 

K 2 Cr 2 7 + 2KOH = 2K2C1O4 + H 2 0. 

Tests for Chromium. 

1. Compounds of chromium, when heated on platinum foil 
with potassium chlorate and carbonate, give a yellow color. 

2. Green color to borax bead. 
In salts of chromium, as, Cr 2 Cl 6 : 

3. Ammonium hydroxide, or sulphide, gives a green pre- 
cipitate of chromic hydroxide. 

4. Potassium, or sodium hydroxide, gives the same precipi- 
tate, soluble in excess, 

In chromates, as, K 2 Cr0 4 : 

5. Hydrogen sulphide in acid solution gives a green color. 

6. Solutions of lead salts give yellow precipitate soluble in 
HC1 and NaOH; insoluble in acetic acid. 

7. Solution barium chloride gives yellow precipitate. 

8. Silver and mercurous nitrate give red precipitate in 

neutral solutions. 

COBALT. 

Symbol, Co. Atomic Weight, 58. Quantivalence, II. and IV. 

Occurrence in Nature. As sulphide, as arsenide and arsenate, and 
as cobaltic oxide. 

Preparation. By heating cobaltous oxide with carbon, or in a cur- 
rent of hydrogen. 

Properties. A reddish-white, lustrous metal; very tenacious and dif- 
ficult to fuse; specific gravity, 8.9; permanent in air, not affected by 
water. Nitric acid dissolves it readily, but it is not much affected by 
hydrochloric or sulphuric acids. Cobaltous compounds are the ones it 
usually forms, and they are isomorphous with ferrous salts. Anhy- 
drous salts have a blue color; hydrous salts, a reddish color. 

Cobaltous Chloride, C0CI2. Made by dissolving cobaltous oxide in 
hydrochloric acid and crystallizing. 

Properties. Red, prismatic crystals containing six molecules of water. 
When heated it becomes anhydrous and turns blue. 

Cobaltous Nitrate. Made by dissolving the oxide or metal in nitric 
acid. Forms red, deliquescent prisms ; soluble. 



202 TEXT-BOOK OF CHEMISTRY 

Tests for Cobalt. 

1. Ammonium sulphide gives a black precipitate of sulphide. 

2. KOH, or NaOH, gives a blue precipitate, which turns pink on 
boiling. 

3. NH4OH gives blue precipitate soluble in excess. 

Sodium Cobaltic Nitrite formed by action of sodium nitrite on solu- 
tion of cobaltous nitrate — Co 2 (N0 2 )6.6NaN02. Used in solution as test 
for potassium, giving yellow precipitate. 

NICKEL. 

Symbol, Ni. Atomic Weight, 58. Valence, II. and IV. 

Occurs free in meteorites ; in combination as sulphide, arsenide and 
silicate, frequently with cobalt. The pure metal obtained by heating 
oxide or carbonate in hydrogen. 

Properties. Silver-white, lustrous, tenacious, specific gravity, 9.1; 
not affected by air; not easily dissolved in HC1 or H2SO4, but easily in 
HNO3. Most of its salts of the ous form. Used with copper and zinc 
in German silver, nickel-steel armor plate, nickel plate. 

Nickelous Sulphate, NiSC^H^O. Made by dissolving oxide in 
H2SO4. Forms green crysals, soluble in water, isomorphous with mag- 
nesium sulphate. 

Tests for Nickel. 

1. (NH 4 ) 2 S: black precipitate. 

2. Sodium or potassium hydroxide gives a green precipitate, unal- 
tered by boiling. 

3. Ammonium hydroxide gives a green precipitate, soluble in excess. 

ZINC. 

Symbol, Zn. Atomic Weight, 65. Valence, II. 

Occurrence in Nature. Zinc is somewhat abundant, occur- 
ring in nature in combination as the carbonate, the silicate and 
sulphide, or zinc blend; sometimes as red oxide, or zincite. 

Preparation. By heating the carbonate or oxide with char- 
coal in clay tubes, when the liberated metal distills : 

ZnO + C = Zn + CO. 

Properties. A bluish-white metal; very little affected by 
the air. It has a crystalline structure, and is brittle at ordinary 
temperatures. Its specific gravity is J.2. Zinc, when heated 



THE METALLIC ELEMENTS '203 

to 120° or 150 , becomes malleable, and may be beaten into 
leaves or drawn out into wire ; it retains these properties when 
cooled. At 200 it becomes brittle again. It fuses at 410 and 
volatilizes at 1000 , if air be excluded. With access of air it 
burns to zinc oxide, giving a bluish-white light. Owing to its 
permanence in the air, zinc is much used in the metallic state 
in the form of sheet zinc and for galvanizing iron. It is used 
also in many valuable alloys, as brass and German silver. 

Zinc forms but one class of salts, in which it is bivalent; 
nearly all of its salts are white. 

Zinc Oxide, Zinc White, Flores Zinci, Lana Philosophica, 
ZnO. Prepared by heating the precipitated basic carbonate, 
when water and carbon dioxide are driven off and the oxide 
remains. Also by burning the metal. Properties: An amor- 
phous, insoluble, tasteless powder. It turns yellow when 
heated, and resumes its white color upon cooling. Found in 
nature as zincite, colored by impurities. 

Zinc Hydroxide, Zn(OH) 2 . Prepared by adding solution 
of an alkaline hydroxide to solution of a salt of zinc, as a white 
amorphous precipitate, soluble in excess of alkali. 

Zinc Chloride, ZnCl 2 . Preparation, By heating zinc in a 
stream of chlorine, or by distilling a mixture of zinc sulphate 
and calcium chloride. Usually prepared by dissolving zinc 
or zinc carbonate, in hydrochloric acid, and evaporating the 
solution to dryness. 

Properties. A white, granular, crystalline powder, or a 
white opaque mass. It is deliquescent, soluble in water and 
alcohol, fuses at 115 , and volatilizes with partial decomposi- 
tion at 68o°. Zinc chloride forms double compounds with 
ammonia (ZnCl 2 NH 3 ) and with potassium chloride; it com- 
bines with albuminoid bodies, and acts as a caustic upon the 
tissues. 

Zinc Bromide, ZnBr 2 , is analogous to the chloride in method 
of preparation and properties. 



204 TEXT-BOOK OF CHEMISTRY 

Zinc Iodide, Znl 2 . Prepared by heating the two elements 
together in water, and evaporating to dryness. 

Properties. Like those of the chloride. 

Zinc Carbonate, Precipitated carbonate of zinc, 2ZnC0 3 - 
3Zn(OH) 2 . Preparation. By boiling together solutions of 
zinc sulphate and sodium carbonate, collecting, washing and 
drying the precipitate : 

5Z11SO4 + 5Na 2 C0 3 + 3H 2 = 2ZnC0 3 .3Zn(OH) 2 + 5Na 2 S0 4 + 2>C0 2 . 

Properties. A white, impalpable, odorless, tasteless powder, 
insoluble in water, soluble in ammonia water and in acids. 

Zinc Sulphate, white vitriol, ZnS0 4 . Preparation. By 
gently roasting zinc blende, or by dissolving zinc in dilute sul- 
phuric acid: 

Zn + H 2 S0 4 = ZnS0 4 + H 2 . 

Properties. Small, colorless crystals, isomorphous with 
magnesium sulphate, containing 7 molecules water of crystal- 
lization, freely soluble in water. 

Zinc Phosphide, Zn 3 P 2 . Preparation. By the action of 
phosphorus upon melted zinc. 

Properties. A grayish-black, insoluble, crystalline solid, 
having a metallic appearance. 

Toxicology. Salts of zinc act as acute irritant poisons, producing 
pain, nausea, vomiting and purging. 

In case of poisoning, milk, albumen and tannic acid act as antidotes. 

Tests for Zinc. 

1. To solution of zinc salt add ammonium sulphide; a white 
precipitate of zinc sulphide is produced. 

2. Add solution of potassium, sodium or ammonium hy- 
droxide; a white precipitate of zinc hydroxide forms, soluble 
in excess. A similar precipitate forms with magnesium com- 
pounds, insoluble in excess of reagent. 



THE METALLIC ELEMENTS 



205 



3. Add solution of potassium f errocyanide ; a white precipi- 
tate of zinc f errocyanide forms; magnesium forms no precipi- 
tate with this reagent. 

4. Add solution of a carbonate, or phosphate, to neutral 
solution of zinc salt; a white precipitate forms. 

Analytical Reactions. 

Directions for analysis of an aqueous solution containing 
one or all of the metals Al, Fe, Co, Ni, Mn, Cr, and Zn. 

To the solution add NH 4 OH until a precipitate remains 
after shaking. Add NH 4 C1, (NH 4 ) 2 S in excess, heat, filter 
and wash the precipitate. The precipitate contains all the 
metals of this group as sulphide, except Cr and Al which exist 
in the precipitate as hydroxides. Stir the precipitate with 
dilute cold HC1. Filter and wash. 



Precipitate. 
Sulphides of Co, Ni. 
Dissolve in nitrohy- 
drochloric acid, evapor- 
ate nearly to dryness, 
add a few c. c. of water, 
and KN0 2 , acidify with 
acetic acid, warm and 
allow to stand. A yel- 
low precipitate of potas- 
sium cobaltic nitrite is 
formed, after several 
hours. Filter, add 
NaOH to the filtrate 
and warm. A green 
precipitate of Ni(OH) 2 
is formed. To another 
portion of the filtrate 
add (NH 4 ) 2 S; a black 
precipitate of NiS is 
formed. 



Filtrate. 
Fe, Zn, Al, Cr, Mn. 
Boil, to expel hydrogen sulphide and add excess of 
bromine water. Make alkaline with NaOH, boil and 
filter. 



Precipitate. 
Fe, Cr, Mn. 
Divide into two portions 
and test as follows : 

1. Dissolve in HC1 and 
test for iron by adding 
K 4 Fe(CN) 6 . Blue color. 

2. Dry and fuse on plati- 
num foil with Na 2 C0 3 and 
KNOg. A green color in- 
dicates Mn. 

Add water, boil, acidify 
with acetic acid and add 
lead acetate. A yellow 
precipitate, if Cr be present. 



Filtrate. 

Al, Zn. 

Make slightly acid with 

HO, add excess of 

NH 4 OH and boil. Al is 

precipitated white. Fil- 



Precipi- 

tate. 

Al 2 (OH) 6 



Filtrate. 
Zn. 
Divide in two 
portions: I. 
Add(NH 4 ) ? S; 
a white precipi- 
tate of ZnS 
forms. 2. Add 
K 4 Fe(CN) 6 
and a few drops 
of HC1 ; white 
precipitate of 
Zn 2 Fe(CN) 6 . 



206 TEXT-BOOK OF CHEMISTRY 

METALS OF THE LEAD GROUP. 

The metals, lead, copper, silver, bismuth, mercury and cad- 
mium constitute the metals of the lead group. They form sul- 
phides which are insoluble in water, ammonium sulphide, or 
dilute mineral acids ; they are, therefore, precipitated by hydro- 
gen sulphide from acid solution, and by ammonium sulphide. 

The metals of this group do not decompose water at any 
temperature, and are not dissolved by dilute hydrochloric or 
sulphuric acids. 

Hot sulphuric acid, and nitric acid dissolve the metals to 
form salts, with replacement of the hydrogen and decomposi- 
tion of part of the acid radical, as shown by the following 

equations : 

Cu + 2H 2 S0 4 = CuSO* + S0 2 + 2H 2 0. 

3 Ag + 4HNO3 = 3AgN0 3 + 2H 2 + NO. 

The oxides, iodides, sulphides, phosphates and carbonates are 

insoluble; the chlorides and sulphates are soluble, with some 

exceptions. 

LEAD (Plumbum). 

Symbol, Pb. Atomic Weight, 205. Valence, II. 

Occurrence in Nature. As sulphide frequently in company 
with silver, and as carbonate. 

Preparation. Almost exclusively obtained from the sul- 
phide, by roasting and heating with coke. Also prepared by 
roasting with access of air, stirring and mixing thoroughly, 
and further roasting without air; the chemical changes taking 
place when the lead ores are roasted with access of air, and the 
further changes occurring when the air is excluded, are shown 
in the following equations : 

PbS + 30 = PbO + S0 2 . ) :., , , . 

Pbs + o, = Pbso*. 1 wlth access of oxygen of air 



PbSO* + PbS = Pb 2 + 2SO 



|- without access of air. 



THE METALLIC ELEMENTS 207 

Properties. A bluish-white, soft metal, whose freshly-cut 
surface shows a bright appearance which soon tarnishes by ex- 
posure. The specific gravity of lead is 11.37; ft fuses at 325 °, 
and distills at a white heat; it burns to the oxide when highly 
heated in the air. 

The metal is not much affected by hydrochloric or sulphuric 
acids on account of the formation of the sulphate or chloride 
on its surface which acts as a protective coating; it will dis- 
solve in these acids when reduced to the form of a fine powder. 
Solutions of lead salts are precipitated by the presence of zinc, 
tin, or iron, the metal being deposited upon these metals in the 
form of fine crystals. 

Lead is largely used in the metallic state in the manufacture 
of alloys, of chemical vessels and of lead pipes. Water con- 
taining air or nitrates is liable to become contaminated by 
passage through lead pipes, but water containing a small quan- 
tity of carbonates or sulphates forms an insoluble protective 
coating on the inner surface of the pipes. 

Lead Oxide, PbO, is prepared by heating lead in a current 
of air, when the lead forms a yellow powder, called " massi- 
cot " ; this, when heated, fuses to reddish-yellow scales of 
" litharge." Further heating of litharge in air results in the for- 
mation of a mixture of PbO and Pb0 2 , or " red lead," which 
is used as a- pigment. 

Lead oxide is used in making the salts of lead, lead plaster, 
paint and glass. 

Lead Nitrate, Pb(N0 3 ) 2 - Preparation: By dissolving the 
oxide in nitric acid, as shown in the equation : 

PbO + 2HNO3 = Pb(N0 3 ) 2 + H 2 0. 

Properties. A white, soluble salt; sweetish, astringent, 
metallic taste. 

Basic Carbonate of Lead, White Lead, 2PbC0 3 .Pb(OH) 2 . 



208 TEXT-BOOK OF CHEMISTRY 

Preparation. By boiling lead nitrate with the oxide, and 
precipitating by C0 2 . Also prepared by action of vapors of 
acetic acid and carbon dioxide on lead. 

Properties. White, insoluble powder; used with linseed oil 
in making paint. 

Lead Iodide, Pbl 2 . Preparation: By mixing solutions of 
potassium iodide and lead nitrate, and filtering out the pre- 
cipitate. The following equation shows the reaction : 

Pb(N0 3 ) 2 + 2KI = PbL + 2KNO3. 

Properties. Heavy, yellow powder; insoluble in water, 
soluble in hot solution of ammonium chloride. 

Lead Sulphate, PbS0 4 , is prepared by adding a solution of 
sodium sulphate to a solution of lead nitrate, when the lead 
sulphate forms as a white precipitate, which is separated by 
filtration. The following equation represents the formation 
of this salt : 

Pb(N0 3 ) 2 + Na.SO* = 2NaN0 3 + PbSCX, 
Properties. A white, insoluble, tasteless powder. 

Toxicology of Lead. Lead poisoning occurs in two forms, acute and 
chronic. Acute lead poisoning occurs from the ingestion of a soluble 
salt of lead, or of the finely divided metal. The chief symptoms are a 
sense of constriction in the throat and pharynx, abdominal pain, stiff- 
ness of the abdominal muscles, paralysis of the lower extremities, scanty 
urine, blueness of the gums and great prostration with convulsions. 
The antidote is diluted sulphuric acid, and magnesium sulphate. The 
stomach should be emptied. 

Chronic Lead Poisoning occurs in those engaged in the manufacture 
or use of lead or its salts, or in those who drink water which has been 
contaminated with the metal. The chief symptoms are as follows : A 
blue line on the gums ; pallor ; emaciation ; quick, feeble pulse ; obstinate 
constipation ; attacks of colic ; paralysis of the extensor muscles of the 
fore-arm, or " wrist drop." The treatment consists in the use of saline 
purgatives, diluted sulphuric acid, followed by the use of potassium 
iodide and galvanism of the paralyzed muscles. 



THE METALLIC ELEMENTS 209 

Tests for Lead. 

1. Hydrogen sulphide, or ammonium sulphide gives black 
precipitate, insoluble in dilute hydrochloric acid or ammonium 
sulphide. 

2. Sulphates give a white precipitate. 

3. Potassium iodide gives a yellow precipitate, soluble in 
hot solution of ammonium chloride. 

4. Potassium chromate gives a yellow precipitate. 

5. Caustic potash gives a white precipitate, soluble in ex- 
cess — plumbates, K 2 PbO s . 

6. Ammonia water gives a white- precipitate, insoluble in 
excess. 

7. Dilute hydrochloric acid in cold, strong solutions of lead 

salts, gives white, granular precipitate, soluble in boiling 

water. 

COPPER (Cuprum). 

Symbol, Cu. Atomic Weight, 63. Valence, II. 

Occurrence in Nature. Copper is found in nature as the 
sulphide, or copper glance; as the carbonate and hydroxide, in 
the green mineral, malachite; as the oxide ; sometimes in the 
free state. The metal also occurs as copper and iron sulphide, 
Cu 2 FeS 2 , in copper pyrites. 

Preparation. By heating the oxide or carbonate with 
carbon. 

Properties. A red, soft, malleable, ductile metal. Specific 
gravity 8.9 ; fuses at 1054 ; forms coating of copper carbonate 
in moist air; burns to black oxide when highly heated in air. 
The metal is not much affected by dilute sulphuric or hydro- 
chloric acids ; with strong sulphuric acid it forms copper sul- 
phate, evolving sulphur dioxide; with nitric acid it forms 
copper nitrate with evolution of nitrogen dioxide. Zinc and 
iron precipitate copper from solution of its salts. 

The metal is largely used in making alloys, copper vessels 
and wire. 



2 10 TEXT-BOOK OF tlHEMISTRY 

Copper forms two classes of salts, cuprous and cupric com- 
pounds ; it is univalent in the former and bivalent in the latter. 
The cuprous salts are very unstable, passing into the cupric 
form. 

Cupric Oxide, Black Oxide of Copper, CuO. Prepared by 
heating copper in the air, by heating the nitrate, or carbonate, 
or by boiling the precipitated hydroxide. 

Properties. A black, insoluble, amorphous powder. Used 
for preparing copper salts and for analyzing organic bodies. 

Cuprous Oxide, Cu 2 0. Prepared by boiling a solution of 
copper sulphate, potassium hydroxide and glucose, when it 
separates as a reddish-brown crystalline powder. 

Cupric Sulphate, Blue Vitriol, Bluestone, CuS0 4 .5H 2 0. 
Prepared by carefully roasting cupric sulphide, or by dissolv- 
ing cupric oxide in sulphuric acid, and crystallizing: 

CuO + H 2 S0 4 = CuS0 4 + H 2 0. 

Properties. Large, transparent, blue, prismatic crystals ; 
nauseous, metallic, astringent taste; soluble in water, insoluble 
in alcohol; becomes anhydrous at 200 . 

Cupric Carbonate, CuC0 3 .Cu(OH) 2 . The normal salt not 
known, but cupric carbonate and hydroxide is precipitated from 
cupric solutions by adding sodium carbonate. Occurs as a 
bluish-green powder. 

Cupric Chloride, CuQ 2 .2H 2 0. A green, deliquescent, solu- 
ble, crystalline salt. 

Ammonio-Copper Compounds. Compounds of copper 
form double salts with ammonia in which the molecule of 
copper salt combines with two, four and sometimes six mole- 
cules of NH 3 . When ammonia water is added to solution of 
cupric sulphate a deep-blue solution is formed, from which 
large, deep blue crystals may be obtained by evaporation, hav- 
ing the composition, CuS0 4 (NH 3 ) 4 .H 2 0. 



THE METALLIC ELEMENTS 2 I I 

Toxicology of Copper. The salts of copper act as poisons. Culinary 
vessels, made of the metal, if allowed to oxidize by lack of cleanliness, 
will form copper salts with fruit and vegetable juices. The symptoms of 
poisoning by copper are those of an irritant poison ; they are abdominal 
pain, vomiting, purging, great prostration and sometimes jaundice. The 
antidote is egg albumen, and demulcent drinks. 

Tests for Copper. 

1. Ammonium sulphide, or hydrogen sulphide, gives a black 
precipitate. 

2. Sodium, or potassium hydroxide, gives a bluish precipi- 
tate which blackens upon boiling, forming cupric oxide. 

3. Ammonia water causes a pale-blue precipitate which 
quickly dissolves, forming a deep-blue liquid. 

4. Potassium ferrocyanide gives a chocolate-brown precipi- 
tate; not obtained in alkaline solution. 

5. Cupric salts give blue borax bead; cuprous salts, red. 

6. Alkaline carbonates give a pale-green precipitate. 

7. A piece of bright iron wire in acidified solution of copper 
acquires a coating of metallic copper. 

BISMUTH. 

Symbol, Bi. Atomic Weight, 207. Valence, III and V. 

Occurrence in Nature. Usually found in the free state dis- 
seminated in rocks. Sometimes as oxide, Bi 2 O s , or bismuth 
ochre; occasionally as sulphide, Bi 2 S 3 , or bismuthite. 

Preparation. Made by mechanical means, by heating the 
ore in iron tubes inclined so as to allow the melted metal to 
run out into suitable vessels. 

Properties. Isomorphous with arsenic and antimony. A 
brilliant grayish-white metal; hard, brittle, and may be easily 
reduced to powder. When melted it expands in solidifying. 
Specific gravity, 9.83 ; melts at 264 ; permanent in the air ; 
insoluble in hydrochloric acid, soluble in nitric and hot sul- 
phuric acid. Frequently contains arsenic as an impurity, which 



212 TEXT-BOOK OF CHEMISTRY 

may be removed by heating with potassium nitrate and hy- 
droxide. 

The compounds show a tendency to decompose with water 
to form oxy- or sub-salts, in which the radical (BiO) behaves 
like a univalent atom. Used for preparation of its salts and in 
alloys. 

Bismuth Trichloride, BiCl 3 . Made by dissolving the metal 
in nitro-hydrochloric acid, evaporating to dryness and dis- 
tilling the residue. 

Properties. A white, deliquescent mass ; fusible and vola- 
tile ; soluble in alcohol ; known as bismuth butter. By mixing 
the alcoholic solution with much water, forms a white insoluble 
crystalline powder of basic bismuth chloride, BiOCl. 

Bismuth Sub-Iodide, or Oxy-Iodide, BiOI. Prepared by 
boiling together solutions of bismuth subnitrate in nitric acid, 
and potassium iodide in water, when the precipitate formed is 
washed and dried. It occurs as a brick-red insoluble powder, 
and is used as an antiseptic dressing, like iodoform. 

Bismuthyl Nitrate, Bismuth Subnitrate, (BiO)N0 3 .H 2 0. 
Preparation. When metallic bismuth is dissolved in nitric 
acid, the normal nitrate forms, and may be obtained by crys- 
tallization from the solution in colorless, transparent crystals : 

Bi 2 + 4HNO3 = 2Bi(N0 3 ) 3 + 2H 2 -f- NO. 

Bismuth Nitric acid Bismuth nitrate Water ^dioxidT 

If the solution of bismuth nitrate thus formed be poured into 
a large quantity of water, the subnitrate separates as a white 
powder, which may be washed and dried for use : 

Bi(N0 3 ) 3 + 2H 2 = (BiO)N0 3 H 2 + 2HN0 3 . 

Bismuth nitrate Water Bismuth subnitrate Nitric acid 

Properties. A white powder, almost insoluble in water, 
insoluble in alcohol, soluble in nitric and hydrochloric acids. 
When heated to redness it gives off nitrous fumes, and leaves 



THE METALLIC ELEMENTS 213 

a yellow residue of oxide, soluble in nitric or hydrochloric acid. 

Uses. Largely used in medicine, and used in cosmetics 
under the name of flake white. 

Bismuth Subcarbonate, Bismuthyl Carbonate, Basic Bis- 
muth Carbonate, (BiO) 2 C0 3 .H 2 0. (Pearl white.) 

Preparation. By mixing a solution of sodium carbonate 
and solution of bismuth nitrate, collecting, washing and drying 
the precipitate : 

2Bi(N0 3 ) 3 + 3Na 2 C0 3 + H 2 = 6NaN0 3 + 2CO2 + (BiO) 2 C0 3 H 2 0. 

T3;,.„,„..u „•* „* Sodium w . Sodium Carbon Bismuth 

Bismuth mtrate carbonate Water ^^ dioxide sub carbonate 

Properties. " A white or pale, yellowish-white powder," in- 
soluble in water, soluble in nitric or hydrochloric acid with 
effervescence. When heated, water and carbon dioxide are 
driven off and the yellow oxide is left (Bi 2 O s ). Used in 
medicine. 

Tests for Bismuth. 

1. Hydrogen sulphide or ammonium sulphide when added 
to solution of bismuth salt will produce a dark brown pre- 
cipitate. 

2. Solution of bismuth salt poured in much water gives a 
white precipitate of oxysalt. 

3. Solution of hydroxides or carbonates of the alkalies give 
a white precipitate. 

4. Solution of potassium iodide gives a brown precipitate, 
soluble in excess. 

5. Solution of potassium dichromate gives a yellow pre- 
cipitate. 

6. Dry reaction. Bismuth or its compounds mixed with sul- 
phur and potassium iodide, and heated on charcoal in blowpipe 
flame, give a red incrustation of bismuthyl iodide. 



214 TEXT-BOOK OF CHEMISTRY 

SILVER (Argentum). 

Symbol, Ag. Atomic Weight, 107. Quantivalence, I. 

History. Well known to the ancients. Called Luna by 
the alchemists. 

Occurrence in Nature. Free, in masses, sometimes. In 
combination with chlorine, bromine, iodine, sulphur and arsenic. 
Occurs most abundantly as sulphide Ag 2 S or silver glance; 
frequently found in company with lead as argentiferous galena. 
The native chloride is known as horn silver. 

Preparation. The extraction of silver is accomplished in 
several different ways, only one of which need be mentioned. 
It is largely obtained from lead made from argentiferous 
galena by the Pattison process, which consists in melting the 
alloy and allowing it to cool slowly, when lead crystallizes first 
and is dipped out with a perforated ladle. The remaining 
alloy, rich in silver, is heated in a porous crucible in a current 
of air, which oxidizes the remaining lead and leaves metallic 
silver as a button in the bottom of the crucible. 

Properties. A pure white, lustrous metal, taking a high 
polish. It is soft, ductile and malleable, and can be made into 
fine wire or foil; comes next to gold in this respect; can be 
beaten to leaf .00025 m.m. in thickness, and wire so fine that 
180 metres weigh 0.1 gm. Thin films transmit green light. 
Specific gravity 10.5 ; melts at 940 ; vaporized in oxy-hydro- 
gen flame, vapor green. Not affected by oxygen, but absorbs 
twenty-two times its volume of oxygen when molten, which it 
gives up upon cooling; it is oxidized by ozone. 

While silver is not affected by oxygen, it is readily tarnished 
by the presence of hydrogen sulphide, which turns it black. 
The metal is capable of existing in several allotropic forms, 
all of which have decided color, and are formed by precipi- 
tating the metal from solution by the action of reducing agents. 

Silver unites directly with the halogens to form salts. It 
dissolves in hot, strong sulphuric acid. 



THE METALLIC ELEMENTS 21 5 

2Ag + 2H 2 S0 4 = Ag 2 S0 4 + 2H 2 + S0 2 . 

It is not much affected by hydrochloric acid or by dilute sul- 
phuric acid in the cold. It is very soluble in nitric acid : 

3 Ag + 4HNO3 = 3AgN0 3 + 2H 2 + NO . 

Silver is too soft for use in the arts pure ; generally alloyed 
with 10 per cent, of copper. 

Chemically Pure Silver is prepared by dissolving in nitric 
acid, precipitating the solution with sodium chloride, and heat- 
ing with sodium carbonate: 

2AgCl + Na 2 C0 3 = 2NaCl + C0 2 + O + Ag 2 . 

Silver Chloride, AgCl, occurs in nature as horn silver. 
Prepared by adding HC1 to solution of silver nitrate. It is a 
white insoluble powder, turning dark by exposure; soluble in 
ammonia water. 

Silver Nitrate, AgNO s . Preparation. By dissolving pure 
silver in nitric acid, evaporating to dryness and heating to 
expel remaining nitric acid. The residue is redissolved in 
water and crystallized. 

Properties. White, transparent, shining, tabular crystals; 
decomposed by light and organic matter; soluble in water and 
alcohol. In making a solution of silver nitrate, pure distilled 
water is necessary, in order to prevent decomposition of the salt. 
This salt acts as a caustic upon the tissues of the body, being 
decomposed by them, with liberation of nitric acid and finely 
divided metallic silver. Luna caustic is silver nitrate, contain- 
ing four per cent, of HC1, moulded into pencils for use as a 
caustic. Mitigated caustic contains one part AgNO s and two 
parts KNO3. 

Silver Oxide, Ag 2 0. Preparation. By adding solution 
caustic potash to solution silver nitrate, collecting, washing and 
drying the precipitate: 

2AgN0 3 + 2KOH = 2KNO3 + H 2 + Ag 2 0. 



2l6 TEXT-BOOK OF CHEMISTRY 

Properties. Dark-brown, insoluble powder. A strong base, 
easily reduced by oxidizable bodies. 

Silver Iodide, Agl. Made by adding solution potassium 
iodide to solution silver nitrate, collecting, washing and drying 
the precipitate. 

Properties. Insoluble, yellow powder. 

Poisoning by silver occurs from ingestion of the soluble 
salts of the metal ; they act as corrosive irritants. The antidote 
is sodium chloride, to form the insoluble silver chloride; and 
demulcent drinks, to allay the irritation. 

Tests for Silver. 
i. Hydrogen sulphide, or ammonium sulphide, gives brown 
precipitate. 

2. Hydrochloric acid, or solution of a chloride, gives a 
white curdy precipitate, soluble in ammonia water. 

3. Alkali hydroxides give brown silver oxide as a precipitate. 

4. Solution of potassium iodide gives a pale yellow pre- 
cipitate. 

5. Potassium chromate gives a brick red precipitate. 

MERCURY (Hydrargyrum, Quicksilver). 
Symbol, Hg. Atomic Weight, 199. Valence, II. 

History. Well known to the ancients, and attracted much 
attention on account of its peculiar physical properties. Men- 
tioned in the writings of Aristotle 400 B. C, and it was de- 
scribed by another writer as liquid silver. 

Occurrence in Nature. Found in the free state amalga- 
mated with gold and silver sometimes; more frequently, dis- 
seminated through its ores in small globules. The most abund- 
ant ore is the sulphide, or cinnabar, HgS. Found in Austria, 
Spain, Nevada, Utah, California, Mexico, New Mexico, New 
South Wales, China and Japan. 



THE METALLIC ELEMENTS 217 

Preparation. Prepared by heating the ore in a current of 
air above 360 °, when the sulphur is oxidized and the metal 
passes off as a vapor. The vapor of mercury passes through a 
series of stone chambers and is collected under water; this 
reaction is shown in the equation : 

HgS + 2 = Hg + SO, 

Sometimes the ores are heated with lime, as shown in the 

equation : 

4HgS + 4CaO = CaSO* + 3CaS + 4Hg. 

The metal is sent into commerce in iron bottles containing 
about eighty pounds each, and contains mechanical impurities 
besides lead, tin, silver, bismuth, copper or zinc. It is purified 
by pressing through chamois skin and carefully distilling from 
iron retorts. Metallic impurities are further removed by the 
action of dilute nitric acid. 

Properties. Mercury is a silvery-white liquid, having a 
bright metallic lustre. 

At a temperature of — 39.38 ° it becomes a malleable, ductile 
crystalline solid, and contracts in volume upon solidifying. In 
very thin layers it transmits a violet-blue light; its specific 
gravity is 13.56. 

Mercury volatilizes slowly at ordinary temperatures, and 
boils at 357.25 °, giving a colorless, very poisonous vapor. It is 
insoluble in the usual solvents ; is not dissolved by hydrochloric 
acid, or cold sulphuric. When heated with strong sulphuric 
acid it dissolves, forming the sulphate with liberation of sul- 
phur dioxide; it is easily dissolved by nitric acid, with escape 
of nitrogen dioxide ; it unites directly with CI, Br and I. 

The pure metal is not affected by the oxygen of the air, but 
when other metals are present it becomes gray from thin oxida- 
tion. A globule should not leave a streak when rolled over 
paper, showing absence of lead and tin. 



2l8 TEXT-BOOK OF CHEMISTRY 

The molecular and atomic weight of mercury are the same, 
showing that its molecule contains but one atom. 

Mercury forms two classes of compounds ; the mercurous, in 
which it is apparently univalent, and the mercuric, in which it 
is bivalent. In mercurous salts two atoms of mercury exert 
the quanti valence of two, one unit of attraction in each atom 
being devoted to its fellow. This molecular structure is found 
in mercurous chloride, Hg 2 Cl 2 , and is clearly shown in the 
graphic formula for this compound, thus : 

Hg-Cl 

Hg-Cl 

Uses. For making scientific instruments, for silvering mir- 
rors, for amalgams, and for preparation of compounds. 

Used in medicine in the metallic state in fine state of sub- 
division in blue mass, mercury with chalk, mercurial plaster 
and mercurial, or blue ointment. 

COMPOUNDS OF MERCURY. 

Mercurous Chloride, Calomel, Subchloride of Mercury, 
Protochloride of Mercury, Submuriate of Mercury, Hg* 2 Cl 2 . 
Found native and impure in horn-quicksilver. 

Preparation. Can be made by adding hydrochloric acid to 
solution of mercurous nitrate when it forms as a granular pow- 
der, or by triturating mercuric chloride with mercury and 
subliming. Usually prepared by triturating mercuric sulphate 
with mercury, mixing with sodium chloride, and subliming: 

HgS0 4 + Hg = Hg 2 S0 4 . 

Hg 2 S0 4 + 2NaCl = Na 2 S0 4 + Hg 2 Cl 2 . 

It is then washed with hot water and dried. 

Properties. White, amorphous, insoluble, odorless, tasteless 
powder. Volatilizes without melting. By oxidation it has a 



THE METALLIC ELEMENTS 2ig 

tendency to pass into the mercuric salt. Calomel is decom- 
posed by the action of strong mineral acids, alkaline hydroxides, 
carbonates, bromides and iodides, and is therefore incompatible 
with these compounds. Calomel is often prescribed with sugar 
or sodium bicarbonate to prevent oxidation. 

Mercuric Chloride,- Bichloride, Corrosive Sublimate, Per- 
chloride, Sesquichloride, Corrosive Chloride of Mercury, 
HgCl 2 . 

Preparation. By subliming a mixture of .mercuric sulphate 
and sodium chloride : 

HgSO* + zNaCl = Na 2 S0 4 + HgCl 2 . 

By dissolving mercuric oxide in hydrochloric acid : 

HgO + 2HCI = HoO + HgO* 

Properties. White, translucent, crystalline masses, forming 
a white granular powder. Odorless, sharp metallic taste. 

Soluble in sixteen parts water, two parts hot water, three 
parts alcohol, fourteen parts glycerine, four parts ether. It 
melts and volatilizes by heat, and its solution has an acid re- 
action. Shows a tendency to form basic chlorides, and double 
chlorides with the alkali metals. This salt is largely used as 
an antiseptic. It acts as a corrosive irritant poison, and the 
antidote is Qgg albumen. 

Mercurous Iodide, Protoiodide, Subiodide, Green Iodide, 
Yellozi' Iodide, Hg 2 I 2 . Can be made by rubbing mercury, alco- 
hol and iodine together in a mortar, when it has a green color. 

Usually prepared by adding solution of potassium iodide 
to solution of mercurous nitrate, collecting the precipitate, 
washing with alcohol, and drying with exclusion of light : 

Hg»(NO«), + 2KI = 2KNO3 + HgJ* 

Properties. A yellow, amorphous, odorless, tasteless, in- 
soluble powder. By exposure to light it becomes darker, form- 



2 20 TEXT-BOOK OF CHEMISTRY 

ing mercury and mercuric iodide; by heat, it melts and sub- 
limes. 

Mercuric Iodide, Biniodide, Red Iodide, Hgl 2 . Can be 
made by direct union of the elements. Usually made by add- 
ing solution of potassium iodide to solution of mercuric chlor- 
ide, collecting, washing and drying the precipitate in the dark : 

H g Cl 2 + 2KI = 2KCI + HgL. 

Properties. A red, amorphous, odorless, tasteless powder; 
insoluble in water, soluble in 130 parts alcohol, soluble in solu- 
tion of potassium iodide or mercuric chloride. Turns yellow 
upon heating, melts and sublimes. Forms double salts with 
iodides. 

Mercurous Oxide, Black or Sub-Oxide, Hg 2 0. Made by 
action of caustic potash or soda on mercurous nitrate : 

H g2 (N0 3 ) 2 + 2KOH = 2KNO3 + H 2 + Hg 2 0. 

Black, insoluble, odorless, tasteless powder. 

Black Wash is made by triturating lime water with calomel, 
and contains calcium chloride and mercurous oxide; its for- 
mation is shown in the following equation : 

Hg 2 Cl 2 + Ca(OH) 2 = CaCl 2 + H 2 + Hg 2 0. 

Mercuric Oxide, HgO. Occurs in two forms; yellow and 
red. 

Yellow Mercuric Oxide, yellow precipitate, is formed by 
adding solution of caustic soda to solution of mercuric chloride, 
washing and drying the precipitate : 

HgCl 2 + 2NaOH = 2NaCl + H 2 + HgO. 

A yellow, amorphous, insoluble powder. 

Red Mercuric Oxide, red precipitate, is formed by heating 

the nitrate, or by triturating the nitrate with mercury and then 

heating : 

Hg(N0 3 ) 2 = 2N0 2 + O + HgO. 

Hg(NOs) 2 + Hg = 2N0 2 + 2HgO. 



THE METALLIC ELEMENTS 221 

It is a granular, crystalline, red, insoluble powder. Not so 
active as the yellow variety because not as finely subdivided. 

Mercurous Sulphate, Hg 2 S0 4 . Prepared by heating strong 
sulphuric acid with an excess of mercury. Separates as a 
yellow, crystalline precipitate when sulphuric acid is added to 
solution of mercurous nitrate. 

Properties. A yellow, crystalline solid. 

Mercuric Sulphate, HgS0 4 . Made by heating mercury 
with excess of sulphuric acid. 

Occurs as a white, crystalline salt. When gently warmed be- 
comes yellow, then red, and finally decomposes. AVhen thrown 
into water it forms the basic salt. 

Yellow Subsulphate of Mercury, Tnrpeth mineral, Hg- 
(HgO) 2 S0 4 . Made by stirring powdered mercuric sulphate 
in a large volume of water. 

Properties. " A heavy, lemon-yellow powder," odorless, 
tasteless and permanent in air. Slightly soluble in water; in- 
soluble in alcohol. Used in medicine as alterative and emetic. 

Mercurous Nitrate, Hg 2 (N0 3 ) 2 . Made by action of cold 
dilute nitric acid on mercury ; the solution allowed to evaporate 
slowly, deposits crystals. 

Properties. White or colorless crystals, soluble in water. 
Decomposed by much water into the basic salt. Used in solu- 
tion as Millon's reagent. 

Mercuric Nitrate, Hg(N0 3 ) 2 . Made by dissolving red 
mercuric oxide in nitric acid, and may be obtained in deliques- 
cent crystals. Used in medicine in " solution of mercury 
nitrate," which contains 60 per cent, of the salt, and has a 
specific gravity of 2.1. Also as " ointment of mercury nitrate " 
(citrine ointment), in which the solution is mixed with fat. 

Mercuric Sulphide, HgS, is found in nature as cinnabar, 
a red mineral. Formed artificially as a black powder by action 
of hydrogen sulphide on solutions of mercury salts, and this 



222 TEXT-BOOK OF CHEMISTRY 

when sublimed forms the red variety. Vermilion is the finely- 
divided sulphide, made by subliming a mixture of sulphur and 
mercury. 

Ammonia forms a number of double compounds with salts 
of mercury. When ammonia water is added to calomel a black 
compound is formed having the formula, NH 2 Hg 2 Cl, mercur- 
ous ammonium chloride. 

By the action of ammonia water upon mercurous nitrate, a 
compound having the formula, NH 2 Hg 2 N0 3 , is produced. It 
was called mercurius solubilis Hahnemanni. 

A number of mercury-ammonium compounds are known, 
and in these compounds the mercury replaces the hydrogen of 
the ammonium radical. 

Mercuric Ammonium Chloride, White Precipitate, NH 2 - 
HgCl, is made by pouring solution of mercuric chloride into 
ammonia water, when it forms as a white precipitate ; this is 
washed and dried at 30 , with exclusion of light: 

HgCl 2 + 2NH4OH = NH 2 HgCl + NH 4 C1 + 2H 2 0. 

Properties. White, brittle, amorphous masses ; odorless, 
earthy, metallic taste ; insoluble in water or alcohol. Used in 
ointments in medicine. 

Tests for Mercury Salts. 

1. Hydrogen sulphide or ammonium sulphide: black pre- 
cipitate. 

2. Ammonium hydroxide : black precipitate with ous salts, 
white with ic salts. 

3. Sodium or potassium carbonate : yellowish precipitate 
with ous salts ; brownish-red with ic. 

4. Potassium iodide : yellowish-green with ous salts ; yellow, 
turning red and soluble in excess with ic salts. 

5. Hydrochloric acid : white precipitate with ous salts ; no 
change with ic. 



THE METALLIC ELEMENTS 



223 



6. Dry mercury compounds heated with sodium carbonate 
give metallic mercury, which forms globules on sides of test 
tube. 

7. Bright metallic copper in solution of mercury salt with a 
drop of hydrochloric acid gives coating of mercury amalgam. 

In poisoning by mercury salts there is salivation, soreness of the 
mouth and gums, abdominal pain, nausea, vomiting and diarrhoea. The 
antidote is egg albumen, which should be administered and then re- 
moved from the stomach, because the compound of albumen with mer- 
cury becomes soluble if it be allowed to remain. 

CADMIUM. 

Symbol, Cd. Atomic weight, 112. Quantivalence, II. 

Cadmium is found in nature as the sulphide, usually associated with 
the ores of zinc. The metal may be obtained by heating the oxide with 
carbon. 

Cadmium is a white metal, having a lustrous appearance and a fibrous 
structure. Its salts show great resemblance in properties to those of 
zinc, but the sulphide differs in having a yellow color and in not being 
soluble in dilute acids. 

The compounds of cadmium are chiefly of scientific interest. The 
sulphate has been employed as an astringent in diseases of the eye: 
the sulphide is used as a yellow pigment. 

Analytical Reactions. 

Directions for analysis of an aqueous solution containing 
one or all of the metals, lead, copper, silver and mercury. 

To the solution add hydrochloric acid, filter, and wash the 
precipitate with cold water. 



Precipitate. 

Pb, Ag, Hg(ous) 

Wash with boiling water. 



Ppt. 
Ag, Hg(ous) 
Add NH 4 OH. 



Ppt. 

Hg. 

Black. 



Filt. 

Ag. 
Add HC1 ; 
Ppt. White. 




Filtrate. 
Pb, Cu, Hg(ic) 
Divide into three portions. 
Sol. 1. Add NH 4 OH ; blue color indi- 
cates copper. 
Sol. 2. Add strip of metallic copper and 

heat ; Hg deposits on the copper. 
Sol. 3. Add H 2 S0 4 , evaporate nearly to 
dryness, and digest with small quantity 
of water ; lead remains as a white in- 
soluble powder. 
(If the white precipitate form upon adding 
the acid no further reaction is required. ) 



224 TEXT-BOOK OF CHEMISTRY 

METALS OF THE ARSENIC GROUP. 

The elements arsenic, antimony, tin, gold, platinum and 
molybdenum are the members of the arsenic group of metals. 
They are precipitated from acid solution by hydrogen sulphide, 
and this precipitate, which is the sulphide of the metal, is in- 
soluble in dilute acids, but soluble in ammonium sulphide or 
alkali hydroxide. In many cases they show a decided non- 
metallic character. 

ARSENIC. 

Symbol, As. Atomic Weight, 74. Valence, III and V. 

Arsenic was known to the ancients in the form of its sul- 
phides. 

Occurrence in Nature. Sometimes in the free state in a 
crystalline form. Found in combination as oxide, As 2 3 , in 
"arsenic bloom"; as disulphide, As 2 S 2 , in realgar, and tri- 
sulphide, As 2 S 3 , in orpiment. The most abundant ore is the 
arsenio-sulphide of iron or mispickel, FeSAs. Sometimes 
found as arsenides of other metals, and in traces in some 
mineral waters. 

Preparation. By heating the oxide with charcoal : 

As 2 3 + 3C = 3CO + As 2 . 

Properties. Arsenic is a steel-gray, metallic, crystalline 
solid ; it is brittle, and can be easily powdered ; its specific 
gravity is about 5.7. When heated to redness, without access 
of air, it volatilizes without fusing ; in the presence of air it 
burns to the oxide. The metal is oxidized in part by exposure 
to moist air. Arsenic enters into direct combination with many 
other elements and, in its compounds, it is capable of taking 
the part of either a metal or non-metal. 

Arsenic shows much resemblance to phosphorus and, like 
that element, forms several allotropic modifications. Amor- 
phous arsenic forms when arsenic is heated in a tube through 



THE METALLIC ELEMENTS 22 5 

which hydrogen is passing, or when arsine is heated as it passes 
through a glass tube; it deposits in the cool part of the tube 
as a black powder, having a specific gravity of 4.7. 

Vapor density of arsenic is 150; molecular weight, 300; it 
therefore has four atoms in the molecule. 

Hydrogen Arsenide, Arsenetted Hydrogen, Arsine, AsH 3 . 
This compound is formed whenever arsenous or arsenic oxides 
or acids or their salts are brought in the presence of nascent 
hydrogen. In properties it is a colorless gas, having a disagree- 
able odor, and exceedingly poisonous when inhaled. It burns 
with a purple flame, forming arsenous oxide and water. If 
the tube through which the gas is passing be heated, amorphous 
metallic arsenic will be deposited just beyond the heated point, 
forming a black coloration. A piece of porcelain held in the 
flame of the burning gas acquires a deposit of metallic arsenic. 
By these means arsenic is easily recognized in Marsh's test. 
See page 228. Antimony salts give the same phenomena. 

Arsenic Trichloride, AsCl 3 . Can be made by passing 
chlorine over arsenous oxide. Usually prepared by heating 
arsenous oxide, sulphuric acid and sodium chloride in a retort, 
and collecting the distillate in a cooled receiver. 

Properties. A colorless, oily liquid, having a tendency to 
form oxysalts when added to much water. 

Arsenic Tri-iodide, Iodide of Arsenic, Asl 3 . Can be made 
by direct union of the elements. More easily prepared by add- 
ing solution of potassium iodide to hot concentrated solution 
of arsenous oxide in hydrochloric acid, when it separates in 
crystals. 

Properties. Red, crystalline masses, slight odor of iodine, 
slowly decomposed by exposure to light; soluble in water and 
alcohol. It is used in Donovan's Solution, Solution of Iodide of 
Arsenic and Mercury, in medicine, which contains one per cent, 
of the iodide of each of these metals. 
16 



226 TEXT-BOOK OF CHEMISTRY 

Arsenic Tribromide is a colorless, crystalline solid, deliques- 
cent and soluble. 

Oxides and Acids of Arsenic. 
Arsenic forms two oxides, which unite with water to form 
acids, showing the non-metallic character of the element: 
they are : 

As 2 3 , Arsenous Oxide; and, As 2 5 , Arsenic Oxide. 

Arsenous Oxide, Arsenous Anhydride, White Arsenic, 
Ratsbane, As 2 O s . Found in nature impure as arseniolite and 
as arsenic bloom. 

Prepared by burning the metal. Also formed by roasting 
ores of metals containing arsenic, and obtained as a by-product. 
The impure oxide is purified by sublimation. 

Properties. A white, slightly granular, crystalline powder, 
having a nauseous, metallic taste. When heated it sublimes 
without melting. It occurs in an amorphous form, as the prod- 
uct of distillation, in transparent, glassy masses, called vitreous 
arsenic. The amorphous variety gradually becomes opaque 
and crystalline. White arsenic is soluble in thirty to eighty 
parts water, the amorphous variety being the more soluble. 

Used in medicine and the arts. Arsenous oxide is one of the 
most common poisons. This, and the other salts of arsenic, 
act as irritant poisons, producing burning pain in the throat, 
esophagus and abdomen; nausea, vomiting, purging and pros- 
tration. The antidote is freshly precipitated ferric hydroxide, 
which forms an insoluble compound with the poison. 

Arsenous Acid, H 3 AsO s , forms when the arsenous oxide is 
dissolved in water : 

As 2 3 + 3H2O = 2H3ASO3. 

Its aqueous solution is colorless, and has an acid reaction. 
It has never been obtained in a pure state. It is tribasic and 
forms arsenites. 



THE METALLIC ELEMENTS 227 

Liquor Acidi Arseniosi, Solution of Chloride of Arsenic of 
the U. S. P., is an aqueous solution of one per cent, arsenous 
oxide and five per cent, diluted hydrochloric acid. 

Liquor Potassii Arsenitis, Fowler s Solution, is made by boil- 
ing one per cent, arsenous oxide with two per cent, potassium 
bicarbonate with water, and coloring the solution with three 
per cent, compound tincture of lavender. 

Arsenic Oxide, Arsenic Pentoxide, As 2 5 . Made by heat- 
ing arsenic acid until water is driven off, when the oxide is 
left as a white, glassy mass, soluble in water to form a solu- 
tion of arsenic acid. 

Arsenic Acid {Ortho-arsenic Acid), H 3 As0 4 , is made by 
warming arsenous oxide with nitric acid, and evaporating to 
a syrupy consistency, when crystals of the acid separate. 

Properties. A colorless, crystalline, soluble solid. By heat- 
ing the acid to 180 water is driven off, and the pyro-acid is 

formed : 

2H3ASO4 — H 2 = H 4 As 2 7 . 

By heating to 200 , two molecules of water are driven off 
and meta-arsenic acid forms : 

2H3ASO4 — 2H 2 = H 2 As 2 6 , or 2HAs0 3 . 

These reactions show the great resemblance of arsenic to 
phosphorus. 

Sodium Arsenate, Na 2 HAs0 4 . May be prepared by neu- 
tralizing arsenic acid with sodium carbonate : 

H 3 AsO, + Na 2 C0 3 = Na 2 HAsO, + H 2 + C0 2 . 
Usually prepared by fusing arsenous oxide, sodium carbonate 
and sodium nitrate together in a crucible, when the pyro- 
arsenate is formed, thus : 

As 2 3 + 2NaN0 3 + Na 2 C0 3 = Na 4 As 2 07 + C0 2 + N 2 3 . 
By dissolving the resulting mass in water and crystallizing, 
the salt is obtained : 

Na4As 2 T + I5H 2 = 2Na 2 HAs0 4 .7H 2 0. 



228 TEXT-BOOK OF CHEMISTRY 

Properties. Colorless, transparent, prismatic crystals ; freely 
soluble in water. Used in medicine in liquor sodii arsenatis, a. 
one per cent, solution in water. 

Sulphides of Arsenic. The elements arsenic and sulphur 
combine directly when heated together to form well-defined sul- 
phides. The sulphides may also be formed by heating sulphur 
with arsenous oxide. Three of these are known — the arsenic 
disulphide, arsenic trisulphide and arsenic pentasulphide. 

Arsenic Disulphide, As 2 S 2 , Realgar, is found in nature. It 
occurs in the form of red, glassy masses; insoluble in water; 
soluble in alkalies. 

Arsenic Trisulphide, As 2 S 3 , Orpiment, is found in nature in 
yellow crystals. It forms when hydrogen sulphide is passed 
through an acidified solution of arsenic, as a yellow powder, 
insoluble in water, soluble in alkalies. With the alkalies it 
forms sulpharsenides, K 2 SAs 2 S 3 . 

Arsenic Pentasulphide, As 2 S 5 , is produced by fusing arsenic 
trisulphide with sulphur, and forms a yellow, fusible mass. 

Tests for Arsenic. 

1. Hydrogen sulphide in acidified solution of arsenic gives 
a yellow precipitate, soluble in ammonium sulphide or alkali 
hydroxide, reprecipitated by an acid. 

2. Ammonio-nitrate of silver gives a yellow precipitate with 
solution of arsenous oxide ; a chocolate brown with arsenic 
oxide; soluble in alkalies and acids. 

3. Bettendorfs Test. Add to arsenic compound dissolved 
in hydrochloric acid, solution of stannous chloride in hydro- 
chloric acid and tin foil and heat ; a brown color forms. 

4. Gutzeit's Test. Mix zinc, sulphuric acid and arsenic in a 
test-tube; fasten filter paper over mouth of tube and moisten 
with silver nitrate and dilute nitric acid; place in dark. Yel- 
low stain forms ; turns brown on moistening with water. Anti- 
mony gives brown stain. 



THE METALLIC ELEMENTS 229 

5. Arsenic compounds heated with potassium carbonate and 
carbon liberate metallic arsenic. 

6. Arsenic compounds heated on charcoal give odor of 
garlic. 

7. Reinsctis Test. The arsenic solution is placed in a test- 
tube, a few drops of hydrochloric acid are added, and a strip 
of bright metallic copper is placed in the liquid. The tube is 
then heated carefully until the liquid boils, when a deposit of 
metallic arsenic appears on the surface of the copper. The 
strip of copper is removed, dried between folds of filter paper, 
and heated in the bottom of a dry clean test-tube. By this 
means the arsenic is volatilized from the copper, and combin- 
ing with oxygen of the air, is deposited on a cool part of the 
tube in the form of crystals of arsenous oxide, which may be 
examined under the microscope. 

8. Fleitmanns Test. A strong solution of caustic soda is 
placed in a small test-tube, a few fragments of zinc are added, 
and then the arsenic solution. A piece of filter paper, moist- 
ened with solution of silver nitrate, is now fastened over the 
open end of the test-tube. When the test-tube is heated, a black 
coloration appears on the filter paper. Antimony does not re- 
spond to this test. The chemical changes taking place in the 
above test are represented in the equation: 

Zn + 2NaOH = Na 2 Zn0 2 + H 2 . 
Nascent hydrogen combines with arsenic to form arsine, 
which in turn produces discoloration on the filter paper by 
liberating metallic silver. 

9. Marsh's Test. The apparatus used in performing this 
test consists of a glass flask provided with a funnel tube and 
delivery tube. The delivery tube is connected with a wider 
tube filled with dried calcium chloride, and this connects with 
a hard glass tube drawn out to a fine calibre at intervals of two 
or three inches, and terminating in a contracted nozzle. Hy- 



230 



TEXT-BOOK OF CHEMISTRY 



drogen is generated in the flask by using zinc and diluted sul- 
phuric acid, and, when all air is expelled, the gas issuing from 
the extremity of the delivery tube is ignited and tested to see 
if the reagents contain arsenic as an impurity. 

Having found that the hydrogen is pure, the arsenical liquid 
is added through the funnel tube. Upon heating the wider 
part of the delivery tube, a dark deposit of amorphous arsenic 



Fig 




Apparatus for Marsh's Test. (After Rockwood.) 



makes its appearance just beyond the heated point at a con- 
striction, and upon placing a cold porcelain surface in the flame 
a dark metallic spot of free arsenic appears. 

The character of the flame after adding arsenic is decidedly 
different from that produced by the burning hydrogen ; it is 
larger, has a purple tint, gives off the odor of garlic, and is 
surmounted by a white cloud of arsenous oxide. 

The reaction of Marsh's test is obtained from arsenic in the 
form of the oxides, their acids or salts, or the chloride; the 
sulphide is not suited for this test, and all organic matter must 
be absent when the test is applied. 

The preparation of an organic substance containing arsenic 
for Marsh's test consists in heating the comminuted substance 



THE METALLIC ELEMENTS 



231 



Fig. 38. 



with water, hydrochloric acid, and potassium chlorate to de- 
stroy the organic matter. The filtered liquid is then treated 
with hydrogen sulphide which precipitates the metals of the 
arsenic and lead groups, if they be 
present ; the washed precipitate is 
treated with ammonium sulphide 
which dissolves out the arsenic and 
antimony; the resulting solution is 
evaporated to dryness and the dry 
residue is heated with sodium car- 
bonate and sodium nitrate, thus form- 
ing sodium arsenate and antimonic 
oxide. By treating the resulting mass 
with warm water the arsenic is dis- 
solved out and may be separated from 
antimonic oxide by filtration. The 
filtrate, containing the arsenic, can 
now be used for Marsh's test. 

Arsenic and antimony give the 
same reactions with Marsh's test, but 
the two spots may be distinguished by 

r J & J Student s Apparatus for 

Several tests, as follows I Marsh's Test. (After 

The arsenic spot is soluble in solu- Rockwood.) 
tion of hypochlorites (calcium or sodium), the antimony spot 
is unaffected. 

Dissolve the spot in nitric acid, evaporate to dryness, and 
add a drop of silver nitrate; a brick-red color forms with the 
arsenic spot, no color with the antimony spot. 

Arsenic spot dissolves with ammonium sulphide and. evap- 
orated to dryness gives a yellow color ; antimony spot treated 
in the same way gives orange-red. 




232 TEXT-BOOK OF CHEMISTRY 

ANTIMONY (Stibium). 

Symbol, Sb. Atomic Weight, 119. Valence, III. and V. 

Occurrence in Nature. Chiefly as the trisulphide, black 
antimony, or stibnite, Sb 2 S 3 ; and with sulphur and metals in 
many ores. Antimony nearly always occurs in company with 
arsenic. 

Preparation. By roasting in air and heating the resulting 
oxide with carbon. 

Properties. A brittle, bluish-white, crystalline metal ; fuses 
at 450 , and volatilizes at a higher temperature when air is 
excluded ; burns when heated in air, forming the oxide ; com- 
bines directly with the halogens ; inflames in chlorine gas. 

Hydrogen Antimonide, Stibine, SbH 3 . Formed by a proc- 
ess analogous to that of hydrogen arsenide. 

Properties. Colorless gas, burns with formation of antimo- 
nic oxide. 

Antimonous Chloride, Trichloride of Antimony, SbCl 3 . 

Preparation. By heating the trisulphide with hydrochloric 
acid, evaporating to dryness and distilling: 

Sb 2 S 3 + 6HC1 = 2SbCl 3 + 3H 2 . 
Properties. A white, crystalline, semi-transparent, soft 
mass, known as butter of antimony, fusing at 73 ° and boiling 
at 223 °. The salt is deliquescent ; it dissolves in water acidified 
with HC1. The solution poured in much water becomes turbid 
from precipitation of the oxy chloride, or powder of Algaroth: 

SbCl 3 + H 2 = SbOCl + 2HCI. 

Antimony Pentachloride, Antimonic Chloride, SbCl 5 . 
Formed by the action of an excess of chlorine on the trichloride. 
It is a yellowish liquid, and fumes in the air. 

The tribromide and tri-iodide are known. 

Oxygen Compounds of Antimony. Antimony forms two 
oxides: Antimonous Oxide, Sb 2 O s , and Antimonic Oxide, 



THE METALLIC ELEMENTS 233 

Sb 2 5 . These resemble the corresponding compounds of 
arsenic. The first has basic properties ; the second, by union 
with water, forms antimonic acid, pyroantimonic acid and 
metantimonic acid, like phosphorus. 

Antimonous Oxide, Antimony Trioxide, Sb 2 3 . 

Preparation. By burning the metal in air. By adding 
sodium carbonate to the solution of the trichloride and heating 
to boiling : 

2SbCl 3 + 3Na 2 C0 3 + H 2 = 2HSb0 2 + 6NaCl + 3C0 2 . 

2HSb0 3 + heat = Sb 2 3 + H 2 0. 

Properties. A heavy, grayish-white powder, soluble in 
hydrochloric acid. This salt dissolves in solution of potassium 
bitartrate, forming tartar emetic. 

Antimonic Oxide, or Pentoxide of Antimony, Sb 2 O s . Prep- 
aration. By action of strong nitric acid on metallic antimony, 
evaporating to dryness, and gently heating the residue. 

Properties. A pale, straw-colored powder. 

Antimonous Acid, Ortho-antimonous Acid, H 3 Sb0 3 , precipitates when 
sulphuric acid is added to tartar emetic solution. A white powder. 

Metantimonous Acid, HSb0 2 , forms when SbCls is decomposed with 
sodium carbonate. A white, amorphous, insoluble powder. 

Antimonic Acid, Ortho-antimonic Acid, HsSbO*. This acid is formed 
when antimony pentachloride is dropped into water. It separates from 
solution as a gelatinous precipitate, of acid reaction, and astringent taste. 
When heated to ioo° it loses water and forms pyro-antimonic acid, 

H 4 Sb 2 0r. 

The sodium salt of pyro-antimonic acid, Na 2 H 2 Sb 2 07.6H 2 0, is remark- 
able in being the only insoluble compound of sodium. 

Metantimonic Acid, HSbOs, forms when pyro-antimonic acid is heated 
to about 200 , or when powdered antimony is heated with nitric acid. 
It is a white insoluble powder, and a weak monobasic acid. 

Compounds of Antimony with Sulphur. 
Antimony Trisulphide, Antimonous Sulphide, Antimony 
Sulphide, Sb 2 S 3 . Occurs in nature with impurities, and sepa- 



234 TEXT-BOOK OF CHEMISTRY 

rated by heating when the sulphide melts and is allowed to 
flow into suitable vessels. 

Properties. Steel-gray, metallic lustre, or dark, grayish 
powder, insoluble in water, volatilized by high heat. The puri- 
fied antimony prepared by washing the above with ammonia 
water. By passing H 2 S through an acidified solution of anti- 
mony, the trisulphide is obtained as an orange-red powder 
which, when heated, is converted into the black variety. 

Sulphurated Antimony, Kermes Mineral, is an oxysul- 
phide of antimony, Sb 2 S 3 Sb 2 3 , and is formed by boiling anti- 
monous sulphide with solution of sodium hydroxide and 
adding sulphuric acid. The precipitate formed is washed and 
dried. 

Properties. A reddish-brown, amorphous powder ; insoluble 
in water, soluble in hydrochloric acid, or sodium hydroxide. 

Antimony Pentasulphide, Golden Sulphur et of Antimony, 
Sb 2 S 5 . Prepared by the action of H 2 S on acid solution of anti- 
monic acid. 

Properties. An orange-red powder which, when heated, de- 
composes to Sb 2 S 3 and S 2 . 



Tests for 

1. With hydrogen sulphide in acid solution compounds of 
antimony give an orange-red precipitate, soluble in ammonium 
sulphide. This precipitate is soluble in strong hydrochloric 
acid — differing from arsenic. 

2. Solutions heated with metallic copper give a black deposit 
of antimony which, when heated in dry test-tube, gives a de- 
posit of antimonous oxide on the glass. 

3. Gutzeit's test gives a brown spot without the antecedent 
yellow seen with arsenic. 

4. Marsh's test gives antimony spot distinguished from 
arsenic spot as described in the tests for arsenic. 



THE METALLIC ELEMENTS 235 

TIN (Stannum). 

Symbol, Sn. Atomic Weight, 118. Valence, II. and IV. 

Occurrence in Nature. As the oxide, Sn0 2 , in " tin stone." 
Sometimes found as sulphide, usually with other metals. 

Preparation. By heating the oxide with carbon. 

Properties. A white, malleable metal, lustrous appearance, 
crystalline. Fuses at 233 ° ; combines directly with most of 
the non-metals ; forms two classes of salts, stannous and stan- 
nic; bivalent in stannous salts and quadrivalent in stannic. 

Stannous Chloride, SnCl 2 (Protochloride). 

Sn + 2HCI = SnCl 2 + H 2 . 

The anhydrous form may be obtained, by heating tin in 
hydrochloric acid gas, as a gray, fatty-looking mass. Usually 
prepared by dissolving tin in hydrochloric acid, boiling down 
and allowing to crystallize. 

Properties. Colorless, prismatic needles ; forms oxy chloride 
with much water ; strong reducing agent — precipitates arsenic, 
mercury, gold, in metallic state. 

Stannic Chloride, Perchloride of Tin, SnCl 4 . May be made 
from stannous chloride by passing chlorine through its solu- 
tion, or by dissolving the metal in nitric and hydrochloric acid 
with aid of heat. 

Properties. A colorless, fuming liquid, combines with 4 
molecules water to form a crystalline compound. 

Test for Tin Salts. 
1. Hydrogen sulphide precipitates stannous salts, brown; 
stannic salts, yellow. 

GOLD (Aurum). 
Symbol, Au. Atomic Weight, 196.7. Valence, I. and III. 
Known from the earliest times. 

Occurrence in Nature. Very widely distributed in nature, 
but usually in very small quantities. Usually found in free 



2 $6 TEXT-BOOK OF CHEMISTRY 

state in granules, often in company with silver, copper, iron, 
or platinum. Sometimes found, though rarely, amalgamated 
with mercury. 

Preparation. Gold is prepared by washing the sand or 
crushed ores in which it occurs, in such a way that the lighter 
material of the ores is carried away, and gold remains in the 
heavy deposit. This deposit is mixed with mercury which dis- 
solves out the gold, forming an amalgam, and the amalgam 
is then heated, driving off the mercury and leaving the gold. 

Properties. Gold is an orange-yellow metal; it is soft, 
malleable, ductile and capable of taking a high polish ; its 
specific gravity is 19.36; its fusing point is 1200 . 

The use of gold in making articles of jewelry and coins is 
supplemented by the addition of copper or silver to give hard- 
ness to the metal. The fineness of jewelry is expressed in 
carats, or twenty-fourths : eighteen carats fineness is eighteen 
parts of pure gold in twenty- four of the alloy, or 18/24 gold 
and 6/24 base metal; fourteen carats is 14/24 gold, and 10/24 
base metal, etc. 

Refined gold is gold from which such metals as copper or 
silver have been removed by treatment with sulphuric or nitric 
acids. 

Gold foil is made by beating gold into exceedingly thin 
sheets ; its malleability being so great as to permit a thinness 
of 1/256,000 of an inch. 

Cohesive gold, used in dentistry, is made by heating gold 
foil to redness: it differs from ordinary gold in having a 
spongy appearance. 

Gold is not affected by any of the strong mineral acids ex- 
cept selenic acid ; it is dissolved by nitro-hydrochloric acid, 
forming the chloride ; it is attacked by chlorine, bromine, or 
mercury. Gold is univalent in aurous compounds ; it is triva- 
lent in auric compounds, the latter are the only salts of interest. 






THE METALLIC ELEMENTS 2^J 

Gold Chloride, AuCl 3 , made by dissolving gold in nitro- 
hydrochloric acid and crystallizing from the solution, is a 
granular, yellow, soluble powder. When this salt is mixed with 
solution of sodium chloride, and the mixed solutions are evapo- 
rated, it forms the chloride of gold and sodium, a yellow, granu- 
lar, soluble solid, used in medicine. 

Tests for Gold. 

1. H 2 S gives brown Au 2 S 3 , soluble in ammonium sulphide. 

2. To a solution of gold salt add solution of ferrous sulphate 
and allow to stand ; metallic gold is precipitated in a fine state 
of subdivision. 

3. Solution of sulphurous acid precipitates metallic gold from 
solution. 

PLATINUM. 

Symbol, Pt. Atomic Weight, 193. Valence, II. and IV. 

Occurrence in Nature. Widely distributed in small quan- 
tity. Occurs free with iridium, osmium, ruthenium and gold in 
grains in sand of rivers, usually. Found in Ural mountains. 

Prepared by treating ores with nitric acid, then hydro- 
chloric acid to remove impurities, and the residue is dissolved 
with hot nitrohydrochloric. The solution of platinum thus 
obtained is precipitated by ammonium chloride, and the pre- 
cipitate heated, leaving spongy platinum, which is fused and 
welded to solid mass. Another method consists in heating 
with lead and lead sulphide, then oxidizing the lead, which 
leaves the platinum. Platinum is melted in a furnace of lime 
by the oxyhydrogen flame. 

Properties. Platinum is a grayish-white metal, rather soft 
and not oxidizable ; it is ductile, malleable and infusible by 
ordinary heat; its specific gravity is 21.15. 

This metal is not soluble in acids except nitrohydrochloric; 
it is attacked by fused alkaline hydroxides, nitrates, sulphides 



238 TEXT-BOOK OF CHEMISTRY 

and cyanides; it has the power to absorb oxygen, but is not 
attacked by this element. 

Platinum black is metallic platinum in a state of fine sub- 
division, obtained from a solution of the chloride as a precipi- 
tate by the action of strong reducing agents : it can be made 
by adding to a solution of the chloride, an alkaline carbonate 
and sugar, and boiling. 

Platinum Perchloride, PtCl 4 .5H 2 0. When platinum is dis- 
solved in nitro-hydrochloric acid and the solution evaporated 
with hydrochloric acid to expel nitric acid, there results chloro- 
platinic acid, PtCl 4 2HC1.6H 2 0. By decomposing one mole- 
cule of this salt with two molecules of silver nitrate, filtering 
the precipitate, the filtrate gives crystals of platinum chloride, 
PtCl 4 .5H 2 0. 

Platinum perchloride is a heavy, brown, deliquescent, solu- 
ble salt, whose solution has a beautiful golden-yellow color. 
This salt is largely used as a reagent for precipitating the salts 
of potassium. 

Tests for Platinum. 

1. To solution of platinum salt add excess of sodium car- 
bonate and some cane sugar and boil ; the platinum is precipi- 
tated as a fine black powder in the metallic state. 

2. Add solution of ammonium chloride; a golden-yellow, 
granular precipitate forms, consisting of the double chloride 
of platinum and ammonium. 

MOLYBDENUM. 

Symbol, Mo. Atomic Weight, 95. 

Molybdenum is found in nature as the sulphide: it is prepared by 
heating the chloride or oxide in a stream of hydrogen. 

In properties molybdenum is a silvery-white, hard, and more infusible 
metal than platinum; its specific gravity is 8.6. 

Molybdenum Oxide, M0O3, is formed by roasting the sulphide; it 
combines with water to form molybdic acid, which unites with alkalies 
to form molybdates. Ammonium molybdate, dissolved in nitric acid, is 
used as a reagent for phosphoric acid, with which it gives a yellow 
precipitate. 



PART IV. 



ORGANIC CHEMISTRY. 

GENERAL CONSIDERATIONS. 

The study of the compounds of carbon constitutes a special 
branch of chemical science. Mainly on account of the great 
number, and partly on account of peculiarities in chemical 
conduct, it is customary to consider these compounds by them- 
selves. The subdivision of General Chemistry into inorganic 
and organic by the older chemists was intended to include 
bodies of mineral origin in the former class, and bodies ob- 
tained from plants and animals in the latter. The supposed 
radical difference in the nature of bodies in the two classes was 
due to a belief that organic substances were formed under the 
mysterious influence of " vital force." 

For a long time it was impossible to form organic bodies 
from the elements, either directly or indirectly, and their pecu- 
liar properties and the complexity of the changes which they 
undergo could not be interpreted in the laws then known. 
Organic and inorganic bodies were therefore regarded in the 
light of substances having essential differences in character. 
Finally, in 1828, Wohler succeeded in preparing urea by arti- 
ficial means. Soon afterwards, many other compounds, which 
hitherto had been obtained only as the product of living tissues, 
were prepared in the laboratory. These, and other experi- 
ments, led to the conclusion that the laws of chemistry apply 
alike to inorganic and organic substances, all being included in 
one great science. 

17 241 



242 TEXT-BOOK OF CHEMISTRY 

The old interpretation of the theory of " vital force " has 
been abandoned, and we know that compounds formed in living 
tissues are not different from the same compounds produced 
artificially. On the other hand, it seems to have been clearly 
shown in recent investigations, that chemical changes occur 
under the influence of cellular activity, which would not occur 
under ordinary conditions. 

Organic chemistry, according to the present views, is the 
chemistry of the compounds of carbon. In accepting this defi- 
nition we must leave out of consideration carbonic acid and 
the carbonates of the metals, but this objection to the term is 
not sufficient for its abandonment. The term, " hydrocarbon 
compounds," has been suggested as an appropriate definition. 

The distinction between organic bodies and organized bodies 
should be clearly drawn at the outset. An organic body is a 
definite chemical compound, such as alcohol, chloroform, 
chloral ; an organized body is rm le up of many different com - 
pounds, it has a characteristic c ;llular structure, and usually 
enters into the formation of some organ of a plant or animal. 

The Elements forming organic compounds are very few, 
when we take into consideration the great number of these 
compounds. The elements carbon, hydrogen, oxygen, nitrogen, 
sulphur, phosphorus and iron are the ones usually present. 
Many hundreds of organic bodies are known which contain 
only carbon and hydrogen, or carbon, hydrogen and oxygen. 
Other elements are sometimes found in organic bodies, and it is 
possible to introduce any element into an organic form of 
combination by artificial means. 

The formation of such a great number of compounds from 
so few elements is explained in the fact that the elements con- 
cerned exhibit extreme differences in physical and chemical 
properties. A further explanation is found in the linking 
power which the atoms of some of these elements possess ; a 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 243 

property which enables an atom to partly satisfy the affinities 
of its fellow, leaving other affinities to be satisfied by the atoms 
of other elements. 

Source of Organic Compounds. Most organic bodies are 
formed by artificial means in the chemical laboratory, but they 
are generally prepared from others which occur ready-formed 
in nature. Crude Petroleum is used for the preparation of a 
great many of these compounds, especially those of the hydro- 
carbon series, and many are prepared from coal-tar, wood-tar 
and bone-oil. Many organic bodies are prepared from others 
by fermentation and destructive distillation. 

The Separation and Purification of organic bodies is accom- 
plished by taking advantage of differences in physical and 
chemical properties. The slightly soluble ones in solution may 
be made to crystallize out, leaving behind the more soluble 
ones, and the " mother liquor " resulting therefrom may be 
made to yield a second crop of crystals, or even a third. This 
is known as fractional crystallization. 

Advantage is taken of differences in boiling point, and they 
are separated by fractional distillation. Those of low melting 
point may be heated to the temperature of fusion and allowed 
to run off from others of higher melting point. Separation by 
making use of chemical properties is accomplished by causing 
a substance to unite with the compound to be removed, or to 
cause its liberation from combination with other bodies, etc. 
Proximate analysis is a term frequently used to indicate the 
separation of organic bodies from each other, as above de- 
scribed. 

Analysis of Organic Compounds. The qualitative analysis 
of an organic compound is of little value except to establish 
the organic nature of the substance. The knowledge that a 
given substance contains carbon and hydrogen, or carbon, 
hydrogen and oxygen, would not indicate what the substance 



242 TEXT-BOOK OF CHEMISTRY 

The old interpretation of the theory of " vital force " has 
been abandoned, and we know that compounds formed in living 
tissues are not different from the same compounds produced 
artificially. On the other hand, it seems to have been clearly 
shown in recent investigations, that chemical changes occur 
under the influence of cellular activity, which would not occur 
under ordinary conditions. 

Organic chemistry, according to the present views, is the 
chemistry of the compounds of carbon. In accepting this defi- 
nition we must leave out of consideration carbonic acid and 
the carbonates of the metals, but this objection to the term is 
not sufficient for its abandonment. The term, " hydrocarbon 
compounds," has been suggested as an appropriate definition. 

The distinction between organic bodies and organized bodies 
should be clearly drawn at the outset. An organic body is a 
definite chemical compound, such as alcohol, chloroform, 
chloral ; an organized body is rru le up of many different com- 
pounds, it has a characteristic c ilular structure, and usually 
enters into< the formation of some organ of a plant or animal. 

The Elements forming organic compounds are very few, 
when we take into consideration the great number of these 
compounds. The elements carbon, hydrogen, oxygen, nitrogen, 
sulphur, phosphorus and iron are the ones usually present. 
Many hundreds of organic bodies are known which contain 
only carbon and hydrogen, or carbon, hydrogen and oxygen. 
Other elements are sometimes found in organic bodies, and it is 
possible to introduce any element into an organic form of 
combination by artificial means. 

The formation of such a great number of compounds from 
so few elements is explained in the fact that the elements con- 
cerned exhibit extreme differences in physical and chemical 
properties. A further explanation is found in the linking 
power which the atoms of some of these elements possess ; a 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 243 

property which enables an atom to partly satisfy the affinities 
of its fellow, leaving other affinities to be satisfied by the atoms 
of other elements. 

Source of Organic Compounds. Most organic bodies are 
formed by artificial means in the chemical laboratory, but they 
are generally prepared from others which occur ready-formed 
in nature. Crude Petroleum is used for the preparation of a 
great many of these compounds, especially those of the hydro- 
carbon series, and many are prepared from coal-tar, wood-tar 
and bone-oil. Many organic bodies are prepared from others 
by fermentation and destructive distillation. 

The Separation and Purification of organic bodies is accom- 
plished by taking advantage of differences in physical and 
chemical properties. The slightly soluble ones in solution may 
be made to crystallize out, leaving behind the more soluble 
ones, and the " mother liquor " resulting therefrom may be 
made to yield a second crop of crystals, or even a third. This 
is known as fractional crystallization. 

Advantage is taken of differences in boiling point, and they 
are separated by fractional distillation. Those of low melting 
point may be heated to the temperature of fusion and allowed 
to run off from others of higher melting point. Separation by 
making use of chemical properties is accomplished by causing 
a substance to unite with the compound to be removed, or to 
cause its liberation from combination with other bodies, etc. 
Proximate analysis is a term frequently used to indicate the 
separation of organic bodies from each other, as above de- 
scribed. 

Analysis of Organic Compounds. The qualitative analysis 
of an organic compound is of little value except to establish 
the organic nature of the substance. The knowledge that a 
given substance contains carbon and hydrogen, or carbon, 
hydrogen and oxygen, would not indicate what the substance 



244 TEXT-BOOK OF CHEMISTRY 

is, because many hundreds of compounds contain the elements 
named. On the other hand, in the study of inorganic bodies, 
to find that a compound is composed of iodine and mercury 
would indicate either mercurous or mercuric iodide, because 
these are the only compounds containing these two elements, 
and a few simple tests would serve to distinguish between the 
two. 

The quantitative analysis for determining the elements of 
an organic body is frequently spoken of as an " elementary, or 
ultimate analysis!' 

i. Qualitative Analysis. The presence of carbon is easily 
shown in many cases by charring of the substance when heated 
on platinum foil. In other cases, when the above test cannot 
be applied, the substance is heated in a glass tube with copper 
oxide which converts carbon into carbon dioxide, and this 
compound may be recognized by passing it into lime water. 

Hydrogen may be determined by heating the substance with 
copper oxide when it is converted by oxidation into water. 
This will condense in a cool part of the tube. 

Nitrogen is determined by heating with dry soda-lime (a 
mixture of one part of sodium hydroxide and two parts of 
calcium hydroxide) when it comes off as ammonia and can be 
recognized by appropriate tests. 

Phosphorus and sulphur are recognized by heating the sub- 
stance with sodium nitrate and carbonate, in a crucible, to form 
sodium phosphate and sulphate. The mass is washed with 
water and the solution tested for these salts. 

Oxygen is not usually determined by qualitative methods. 

2. Quantitative Analysis. The hydrogen and carbon are 
determined by heating the dry substance with copper oxide in 
a combustion tube and collecting and weighing the escaping 
vapors of water and carbon dioxide. The water vapor is col- 
lected in a previously weighed U-shaped tube of dried calcium 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 245 

chloride; increase in weight represents the weight of water 
formed, and from this the weight of hydrogen is easily calcu- 
lated. The carbon dioxide is collected and weighed, in like 
manner, in bulbs containing potassium hydroxide solution, and 
from the weight of carbon dioxide obtained the weight of car- 
bon is calculated. 

Fig. 39. 




Combustion Furnace. (After Bartley.) 

The quantity of nitrogen is determined by heating the organic 
substance with soda-lime and passing the ammonia thus formed 
into hydrochloric acid. The resulting solution is evaporated 
on a water bath, the dry residue of ammonium chloride is 
weighed and from this is calculated the weight of nitrogen. 

Oxygen is determined by difference, after accounting for all 
other elements present. 

Phosphorus and sulphur are converted into phosphoric and 
sulphuric acids as above described, and the quantity of each is 
calculated from the weights of these salts. 

The results of the analysis are usually first expressed in a 
percentage formula. 

For example : 

Analysis of 44 gms. dried organic substance gives : 
88 gms. C0 2 , representing 24 gms. Carbon, 

36 gms. H 2 0, representing 4 gms. Hydrogen, 

and a remainder of 16 gms. Oxygen, 

other elements being absent. — 

44 gms. substance. 



246 TEXT-BOOK OF CHEMISTRY 

Percentage formula: 

24 X 100 

Carbon == = 55 + per cent. 

44 

4X 100 

Hydrogens = 9 + per cent. 

44 

16 X 100 
Oxygen — = 36 -j- per cent. 

44 

100 

The Empirical Formula is the simplest expression of the 
relative numbers of atoms in the molecule, without giving the 
actual numbers. It may be determined from the percentage 
formula by dividing the percentage of each element by its 
atomic weight, and dividing the quotients by the greatest com- 
mon divisor, so as to express these relations in their simplest 
terms. 

For example : 

Carbon, 54.48 per cent., -f- 12 = 4.54 ^ ^ Carbon, 2 

Hydrogen, 9.21 per cent, -f- 1 == 9.21 > -+- 2.27 = > Hydrogen, 4.06 
Oxygen, 36.31 per cent, -r- 16 = 2.27 J J Oxygen, 1 

100.00 
Or, approximately, C2H4O, the empirical formula. 

The Molecular Formula expresses what is included in the 
empirical formula and, in addition to this, it expresses the 
actual number of atoms in the molecule. The molecular for- 
mula is most readily determined from the empirical by taking 
the vapor density of the substance as compared with hydrogen, 
and referring to the law of Avogadro. 

For example : 

If, in the above compound, C 2 H 4 represents its true molecular for- 
mula, the vapor density, when compared with hydrogen, would be 22. 
If its vapor density is found to be 44, its molecular formula would be 
C4H8O2. (See methods for determining molecular weight, page 73.) 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 247 

It is not always possible to vaporize the substance whose 
molecular formula is to be determined and, in these cases, it 
is necessary to study the chemical reactions and decomposi- 
tions. 

Structural, Constitutional, or Graphic Formulas. These 
formulas represent all that is shown in the empirical and 
molecular formula and, in addition, they represent the relative 
arrangement of the atoms in the molecule, the chemical changes 
the compound is likely to undergo, and its relations to other 
compounds. It must be remembered that they are not intended 
to show the actual position in space of the atoms. 

In order to get a clear idea as to the exact significance of a 
graphic formula, it is well to study how such a formula is de- 
termined, thus : 

When the molecular formula has been determined, the next 
thing to be done is to study the compound by physical and 
chemical methods, in order to ascertain just how it behaves 
under all the conditions that can be applied. In this way many 
facts are discovered in reference to the substance — in other 
words, we have acquainted ourselves with many of its proper- 
ties. The next step is to embody these facts in a formula which 
will give them expression. How this is done can be shown 
best by an example. In the case of acetic acid, the molecular 
formula is found to be C 2 H 4 2 . It may be shown that one- 
fourth of the hydrogen can be replaced by a metal (C 2 H 3 K0 2 ), 
and thus it is seen that one of the hydrogen atoms is different 
from the others, since they cannot be replaced. This fact is 
expressed by writing the formula for acetic acid, H.C 2 H 3 2 . 

Again, by treating acetic acid with phosphorus trichloride, a 
compound having the formula C 2 H 3 OCl is formed, and the acid 
loses one atom of hydrogen and one of oxygen. If this chlorine 
compound be treated with water, acetic acid is regenerated by 
entrance of the atom of hydrogen and of oxygen : 

GH3OCI + H 2 = HC1 + C 2 H 4 2 . 



248 TEXT-BOOK OF CHEMISTRY 

This reaction shows that an atom of hydrogen and an atom 

of oxygen are closely associated in the molecule, since they 

leave and re-enter it together. This fact is expressed by the 

formula : 

GHsO.OH. 

The chlorine compound formed in the above experiment con- 
tains no hydrogen that can be replaced by metals, and thus we 
know that the replaceable hydrogen of acetic acid, expressed 
in the formula, H.C 2 H 3 2 , is closely associated with oxygen, 
and is the same as that represented in the formula, C 2 H 3 O.OH. 

By experiments of like nature it can be shown that the other 
oxygen atom is closely associated with a carbon atom, and this 
fact, with the others determined, is expressed by the formula, 
CHg.CO.OH. These facts are determined by analysis and may 
be confirmed by synthesis. 

The synthesis of acetic acid may be accomplished by causing 
marsh gas, CH 4 , to act upon carbonyl chloride, COCl 2 , thus : 

CH 4 + COCl 2 = C.H.OC1 + HCL 

The compound, C 2 H 3 OCl, is found to be identical with the 
one formed by the action of phosphorus trichloride on acetic 
acid, and the correctness of the formula, CH 3 .CO.OH, is 
strongly indicated. 

These formulae are thus seen to express not only the com- 
position of substances but, to a great extent, properties as well. 

When we call to our aid the valency hypothesis, and give 
expression in our formula of the quantivalence of each atom, 
we have a completed graphic formula for acetic acid, thus : 

H 
I 
H — C C — O-H 

I II 

H O 

The graphic formula when viewed in this light is a valuable 
aid to the study of chemistry, but too much importance should 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 



249 



not be attached to the formula itself to the exclusion of that 
which it represents. 

Linking Power of Atoms. The power possessed by some 
atoms of partly satisfying the chemical affinities of other atoms 
of the same or different elements, leaving affinities to be satis- 
fied by other atoms, is known as linking, or chain formation. 
This power is very highly developed in the atoms of carbon 
and oxygen, and is well shown in the types of graphic formulae. 

Types of graphic formulae showing linking power of carbon 
.atoms : 



I. By varying number of valence units— 

H H H H 

II II 

H— C— C— H C=C 

II II 

H H H H 

Ethane Ethene, or ethylene 



H— C=C— H 



Ethine, or acetylene 



2. Simple Chains- 



H 



H H H H H H 
I I I I I I 
C— C— C— C— C— C— H 

I I I I I I 
H H H H H H 

Hexane 



.3. Simple chain with lateral attachment- 

H 

I 
H— C— H 



H- 



H H 

I 
C— C— C— H 

I I I 
H H H 



Trimethy 1-meth ane 



250 


TEXT 


4- 


Simple closed chains- 




H H 

\/ 

C 

H /\ H 

V \/ 

c c 

1 1 




1 1 
H H 




Trimethylene 



TEXT-BOOK OF CHEMISTRY 



H 

// / 

/ c \ / c \ 

I 

H 

Benzene 



\ 



5. Closed chains with lateral attachments- 



H $ V 

// / 

h' x c / w 

/ 

H 

Ethyl-benzene 



6. Multiple closed chains- 



H H 

I I 

H C C H 

c c c 

II I I 

c c c 

H C C H 

I I 

H II 



Naphthalene 



ORGANIC CHEMISTRY — GENERAL CONSIDERATIONS 2$l 

7. Linking of oxygen atoms — 



H H 

1 1 




H H H H 

II II 




H H H H 


H— C— C 


H- 


-c— c— 0— c— c- 


-H 


C C 


1 II 




II II 




/\ /\ 


H 




H H H H 




H \/ H 

C 

II 



Ethyl-aldehyde 




Ethyl-ether 




Acetone 



A Radical is an unsaturated group of atoms behaving, in 
many respects, like a single atom. It is capable of passing as 
a unit from one compound to another in chemical changes. A 
radical may be obtained by removal of one or more atoms from 
a saturated compound but it is not necessary for it to exist 
alone ; in fact, radicals are usually incapable of separate ex- 
istence. The radical of water is hydroxyl, OH, obtained by 
removal of an atom of hydrogen. From marsh gas, CH 4 , four 
radicals may be obtained by removal of one, two, three or four 
atoms of hydrogen. 

Substitution is a chemical change by which an atom, or 
group of atoms, is replaced by another atom, or group of 
atoms. It is a very common form of chemical change in 
organic bodies, and is plainly shown in the following equation 
which represents the replacement of hydrogen in benzene, C 6 H 6 , 
by the radical N0 2 , of nitric acid : 

C 6 H 6 + HON0 2 = C 6 H 5 N0 2 + H 2 0. 

A Derivative is a compound formed from some other by a 
chemical change. Alcohols are derivatives of hydrocarbons, 
formed from them by replacement of hydrogen by the radical 
hydroxyl, thus : 

C 2 H 6 . C 2 H 5 OH. 

Hydrocarbon Alcohol derivative 

An Homologous Series of organic compounds is one in 
which each of the members differs from the next of the series 



252 TEXT-BOOK OF CHEMISTRY 

by the term CH 2 . An homologous series of organic compounds 
is represented thus : 

Crii, C2H6, C3H8, C4H10, C5H12, CeHu, &C. 

An Isologous Series is one in which each member differs 
from the next of the series by the term H 2 . An isologous series 
is represented thus : 

C3H2, C3H4, C3H6, C3H8, &c. 

Isomerism. Bodies composed of the same elements in the 
same proportions by weight are found, in some cases, to possess 
different properties ; these are said to be isomeric with each 
other. Isomeric bodies may be either polymeric or metameric. 

Polymeric bodies are those having the same proportionate 
number of atoms of the same elements in the molecule. These 
formulas represent polymeric bodies : 

C2H2, C4H4, CeHe, &C. 

Metameric bodies are those having the same actual numbers 
of atoms of the same elements in the molecule, the differ- 
ence in properties here depending upon a difference in the 
arrangement of the atoms. Ethyl acetate and butyric acid 
both have the empirical formula C 4 H 8 2 , but the arrangement 
of atoms in ethyl acetate is represented by the formula, 
C 2 H 5 .C 2 H 3 2 ; the arrangement in butyric acid by the formula, 
H.C 4 H 7 2 . 

Stereoisomerism is a form of isomerism dependent upon differences 
in the space relations of the atoms in the molecules of two or more 
compounds, otherwise the same. Two bodies are said to be stereois- 
omeric when they show differences in the geometrical arrangement of 
atoms in the molecule and act differently upon the ray of polarized light. 

The study of stereoisomerism is conducted by making observations 
of the action of bodies upon the ray of polarized light. 

General Properties of Organic Bodies, The properties 
are dependent to a great extent upon the properties of the 
constituent elements. Organic bodies are found as solids, 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 253 

liquids and gases. They are gaseous when the molecule is 
light, and contains a small amount of carbon as compared to 
the hydrogen or oxygen. With increase in the proportion of 
carbon, increase in molecular weight, and increase in specific 
gravity, there is augmentation in the density of the compound 
— passing from a tenuous to a dense gas, from a gas to a liquid, 
and from a liquid to a solid. In this way, compounds contain- 
ing little carbon of small molecular weight are gases ; those 
containing much carbon of great molecular weight are solids. 

Organic bodies show every variety of color, odor and taste. 
Some serve for food, while others are violently poisonous. 
They are combustible, because of this property in carbon and 
hydrogen. They occur as acids, bases and salts. Some are 
active and some are very inert. In short, they present every 
variety of properties; and it is surprising that so few elements 
are capable of forming such a great number of compounds 
showing such dissimilarity. 

Chemical Change in Organic Bodies is promoted by those 
conditions which favor chemical action in general, but the 
character of the reaction is frequently different from that which 
we have seen heretofore. Some of the more important chemical 
changes which have been observed to occur in organic bodies 
are given, as follows : 

1. A rearrangement of the atoms in the molecule, whereby 
the molecular structure of the substance is changed, resulting 
in a corresponding change in properties. This kind of change 
often occurs spontaneously, and is seen in the slow conversion 
of oil of lemon into oil of turpentine by the lapse of time. 

2. Splitting of a molecule into two or more compounds of 
simpler nature. This kind of change can be seen in the forma- 
tion of ethyl alcohol and carbon dioxide from glucose during 
the process of fermentation, thus : 

CeHisOs = 2C 2 H 6 + 2C0 2 . 



254 TEXT-BOOK OF CHEMISTRY 

3. The union of two or more molecules of the same or of 
different kinds, thus : 

C2H4 -J- CI2 = C2H4CI2. 

4. The removal of atoms from a molecule, with or without 
replacement by other atoms, thus : 

C 2 H 6 + Cl 2 = C 2 H,0 + 2HCI. 

Alcohol Chlorine Aldehyde Hydrochloric acid 

C 2 H 4 + 3CI2 = C2HCI3O + 3HCI. 

Aldehyde Chlorine Chloral Hydrochloric 

acid 

Action of Heat Upon Organic Bodies. Some organic 
bodies are volatilized by the action of heat but on account of 
the instability of the molecule many of them are decomposed. 
Heating an organic body in a closed vessel, so as to exclude 
air and form volatile products, is known as destructive distilla- 
tion. The nature of the products formed by destructive dis- 
tillation depend upon the nature of the substance heated and 
also upon the degree of heat employed. The products thus 
formed have a smaller number of atoms in the molecule, and 
are less complex in structure than the original substance. De- 
structive distillation furnishes the means of obtaining a great 
many useful organic compounds, such as wood alcohol, creo- 
sote, carbolic acid, acetic acid, naphthaline, etc. 

Action of Oxygen. On account of the presence of hydro- 
gen and carbon all organic bodies are capable of oxidation. 
Oxidation occurring with sufficient degree of intensity to fur- 
nish heat and light is called combustion. Oxidation may pro- 
ceed slowly throughout a long period of time without light or 
sensible heat; it is then called decay or slow combustion. It 
is worthy of note, that of all organic bodies found in nature 
none contains a sufficient amount of oxygen to oxidize all of 
the carbon and hydrogen found in the molecule ; such bodies 
may be made by artificial means, however, and they constitute 
highly explosive compounds. 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 255 

Products formed by rapid oxidation of organic bodies are 
carbonic acid, water, phosphoric and sulphuric acids, from the 
elements carbon, hydrogen, phosphorus and sulphur, re- 
spectively, when present. 

The ultimate products are the same in rapid and slow com- 
bustion, but when organic bodies undergo slow oxidation 
many intermediate substances are formed before the state of 
complete oxidation is reached. This is shown in the following 
equations which represent the changes occurring in rapid and 
slow oxidation of alcohol. 

Rapid oxidation of alcohol : 



GHeO 


+ 


30 2 


= 2CO2 + 


3H 2 0. 


Alcohol 




Oxygen 


Carbon dioxide 


Water 



Slow oxidation of alcohol : 

C 2 H 6 + O = C2H4O + H 2 0. 

Alcohol Oxygen Aldehyde Water 

QH 4 + O = GHA. 

Aldehyde Oxygen Acetic acid 

Oxidation is facilitated by the presence of warmth and mois- 
ture, and it is indefinitely retarded by keeping the substance 
perfectly dry. 

Fermentation and Putrefaction consist of chemical changes 
in which the molecule of the organic body is split up into two 
or more molecules of simpler composition. For these changes 
to take place three factors are necessary — moisture, favorable 
temperature, and the presence of a ferment. 

The temperatures favoring fermentation and putrefaction 
range between 25 ° and 40 C, or JJ° and 104 F. These 
forms of decomposition are completely arrested or prevented 
by boiling or freezing. 

The ferments consist of nitrogenous bodies, such as pepsin, 
pancreatine, etc., called soluble ferments; and of microscopic 
forms of life, such as the yeast plant, called organized ferments. 



256 TEXT-BOOK OF CHEMISTRY 

A small quantity of the ferment is capable of exciting a great 
deal of chemical action ; this is accompanied by no apparent 
change in the soluble ferment, and only such changes in the 
organized ferment as are incident to life and reproduction. The 
ferments probably have the power of exercising catalytic action 
in causing chemical change in other substances. 

The nature of the ferment frequently determines the char- 
acter of the product formed from a given substance. Lactic 
acid and alcohol are both obtained from sugar by the action 
of different ferments. 

The soluble ferments, also called enzymes, are secreted by 
organized ferments and by living tissue cells. They exist in 
the secreting animal cells in an inactive state, called zymogens, 
which become active on coming in contact with the air, or 
with acids or alkalies. They are soluble in water or glycerine, 
and are precipitated from solution by absolute alcohol. 

Soluble ferments which break down proteins into simpler 
forms are termed proteolytic; those which convert amyloses 
into sugars are called amylolytic ; those which change complex 
to simpler sugars are called glycolytic. 

Soluble ferments are found in the vegetable and animal 
kingdoms, and they generally serve to promote chemical 
changes which contribute to the nutrition of the plant or ani- 
mal. Some of the important ferments found in plants are — 
diastase, from germinating grain; emulsin, from the almond; 
papain, from the pawpaw tree; and bromelin, from the pine- 
apple. Ferments from animal tissues are — pepsin, pancreatine, 
ptyalin, invertase. 

Organized ferments are living microorganisms, chiefly bac- 
teria, and they are capable of producing both normal and patho- 
logical forms of fermentation in the body. Some of the more 
important members of this class are — the yeast fungus ; the 
Mycoderma Aceti, or mother of vinegar ; Oidium Albicans, or 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 257 

thrush fungus; Bacilli Lactici and Bacilli Butyrici, or bacilli 
of lactic and butyric acids ; putrefying, nitrifying, and patho- 
genic ferments. 

Putrefaction is the breaking up of molecules containing one 
or more of the elements sulphur, phosphorus and nitrogen in 
organic combination, and it takes place under the same con- 
ditions as fermentation. These elements are converted into 
hydrogen sulphide, hydrogen phosphide, and ammonia, and 
impart a disagreeable odor to the putrefying substance. 

The products of putrefaction have no value,, but many of 
the bodies formed by fermentation are used in the arts and in 
medicine. 

Fermentation, putrefaction, and decay, or oxidation, all par- 
ticipate in the changes taking place in decomposition of exposed 
animal matter. 

The entrance of pathogenic organized ferments into the 
living tissues is known as infection when the ferments have 
established themselves to the detriment of the host. Antiseptics 
and disinfectants are some of the agents employed to combat 
the infecting bodies. Antiseptics retard the growth and de- 
velopment of infecting organisms. Disinfectants destroy the 
infecting material. Deodorants destroy or remove offensive 
odors. 

Action of Nitric Acid on organic bodies results in the for- 
mation of three different classes of compounds : 

1. The acid unites with organic bases to form salts, or 
nitrates ; an action similar to that seen in inorganic chemistry. 

2. Nitro-compounds may be formed, in which the radical 
N0 2 , from nitric acid, enters the organic molecule. 

3. Simple oxidation may take place, in which the nitric 
acid gives up its oxygen to the organic substance. 



258 TEXT-BOOK OF CHEMISTRY 

CLASSIFICATION OF ORGANIC BODIES. 

All organic bodies may be regarded as being derived from 
hydrocarbons, and since the hydrocarbons can be divided into 
two great groups — fatty and aromatic — we have a correspond- 
ing arrangement for their derivatives. 1. Fatty Compounds 
are those derived from methane, or marsh gas, CH 4 . 2. 
Aromatic Compounds are those derived from benzene, C 6 H 6 . 

Organic bodies are further arranged in the following groups, 
for convenience of study, in accordance with chemical com- 
position and structure: 

1. Hydrocarbons are compounds containing the elements 
carbon and hydrogen. 

Examples : CH 4 , C 2 H 6 . 

Methane Ethane 

2. Alcohols are hydrocarbon radicals in combination with 
hydroxyl, OH. 

Examples : CH 3 OH, C 2 H 5 OH. 

Methyl alcohol Ethyl alcohol 

3. Aldehydes are hydrocarbon radicals in combination with 
COH, formed in the first stage of oxidation of primary alcohols 
by the removal of hydrogen. 

Examples : CH 2 0, C2KLO. 

Methyl Ethyl 

aldehyde aldehyde 

4. Ketones are hydrocarbon radicals in combination with 

the group CO. 

Example : ( CH 3 ) 2CO. 

Dimethyl ketone 

5. Acids are hydrocarbon radicals in combination with the 
group, HC0 2 , denominated carboxyl. 

Example: CH 3 (C0 2 H). 

Acetic acid 

6. Ethers are the oxides of hydrocarbon radicals. 

Examples: (C 2 H 5 ) 2 0, (CH 3 ) (C 2 H s )0. 

Ethyl ether Methyl -ethyl ether 



ORGANIC CHEMISTRY GENERAL CONSIDERATIONS 259 

7. Compound Ethers, or Esters, are the salts formed by 
the union of hydrocarbon radicals with acid radicals. 

Example : ( C 2 H 5 ) C2H3O2. 

Ethyl acetate 

8. Carbohydrates generally contain six atoms of carbon, or 
some multiple of six, in combination with hydrogen and oxygen 
in the proportion to form water. They are aldehydes and 
ketones of the hexatomic alcohol mannitol. 

Examples : Sugars, starch, &c. C 6 Hi Ob. 

9. Amines and Amides are compounds formed by replace- 
ment of the hydrogen of ammonia by alcohol or acid radicals. 

Examples : C 2 H 5 NH 2 , C 2 H 3 ONH 2 . 

Ethylamine Acetamide 

10. Cyanogen and its derivatives contain the radical, CN. 

Example : HCN. 

Hydrocyanic acid 

11. Diazo and Azo compounds contain the radical N 2 . 

Examples: C 6 H 5 N 2 C1, (C 6 H 5 ) 2 N 2 . 

Diazo-benzene Azo-benzene 

chloride 

12. Hydrazines are formed by replacing hydrogen in the 
compound, hydrazine, N 2 H 4 . k 

Example : C 6 H 5 N 2 H 3 . 

Phenyl hydrazine 

13. Pyridine Bases are compounds containing nitrogen in 

the benzene nucleus. 

Example : C 5 H 5 N. 

Pyridine 

14. Pyrrole Derivatives are formed by replacing hydrogen 

in pyrrole, C 4 H 5 N. 

Example : CHLN. 

Iodol 

15. Alkaloids are feebly basic substances containing nitro- 
gen. They belong to the group of amines and amides. 

Examples : C 8 H 1T N, C 2 iH 22 N 2 2 . 

Conine Strychnine 



260 TEXT-BOOK OF CHEMISTRY 

1 6. Ptomaines are feebly basic substances, containing nitro- 
gen, formed by the action of bacteria on nitrogenous organic 
matter. 

Example : Cadaverine. 

17. Leucomaines are nitrogenous basic substances, formed 
as products of tissue metabolism in the living body. 

Examples : Creatine, Adenine. 
Compounds of undetermined composition comprise : 

1. Glucosides, or bodies which when decomposed give glu- 
cose as one of the products. 

Example : Amygdalin. 

2. Bitter Principles, of vegetable or animal origin, crystal- 
line and amorphous. 

Examples : Aloin, chlorophyll, biliary pigments. 

3. Proteids containing carbon, hydrogen^ oxygen, nitrogen 
and sulphur, and sometimes other elements. 

Examples : Albumen, myosin, casein, &c. 

HYDROCARBONS. 

Definition. A compound containing carbon and hydrogen 
as its constituent elements. 

Occurrence in Nature. Usually found as a direct or indi- 
rect product of vegetable life. They are formed in the tissues 
of plants by a series of chemical changes from carbon dioxide 

and water : 

ioC0 2 + 8H 2 = C 10 H 16 + 28O. 

Also produced in nature by the decomposition of vegetable 
substances in the presence of moisture, and during the forma- 
tion of coal in the interior of the earth. 

Formation of Hydrocarbons by Artificial Means. Carbon 
and hydrogen do not readily enter into direct chemical union, 
but the compound acetylene, C 2 H 2 , can be made by passing 



HYDROCARBONS 26 1 

a current of electricity between electrodes of carbon in an 
atmosphere of hydrogen. The hydrocarbon marsh gas, CH 4 , 
can be made by passing the vapors of carbon bisulphide and 
water, or hydrogen sulphide, over red-hot metals, as shown 
by the equations : 

CS 2 + 2H 2 S + 8Cu = 4 Cu 2 S + CH 4 . 

CS 2 + 2H 2 + 6Cu = 2Cu 2 S + 2CuO + CH 4 . 

These reactions are of great interest, for they show the pos- 
sibility of forming organic bodies from the elements, since car- 
bon bisulphide, hydrogen sulphide and water are all easily 
formed from elementary substances. 

Many hydrocarbons are produced by the destructive distilla- 
tion of organic bodies. Other forms of decomposition of 
organic bodies sometimes result in the production of hydro- 
carbons. For example, by heating calcium acetate with sodium 
hydroxide marsh gas is formed, thus : 

Ca(C 2 H 3 2 ) 2 + 2NaOH = 2CH 4 + Na 2 C0 3 + CaC0 3 . 

Calcium acetate Sodium hydroxide Marsh gas Sodium Calcium 

carbonate carbonate 

The hydrocarbons found in nature and most of those pro- 
duced by artificial means have to be separated from impurities 
and from each other by fractional distillation, crystallization, 
and differences in solubility, melting point, and other proper- 
ties, before the individual members can be studied. 

General Properties of the Hydrocarbons, The number of 
hydrocarbons is very great, and the possible number is almost 
unlimited on account of the linking power of carbon atoms and 
the isomeric modifications. They are found in all three states 
of aggregation, their position in this respect depending upon 
the proportion of carbon in the molecule, and the molecular 
weight of the individual compound. Those containing not 
more than four (4) carbon atoms to the molecule are generally 
gases, from 4 to 12 liquids, and those having more than 12 



262 



TEXT-BOOK OF CHEMISTRY 



carbon atoms are usually solids. All are volatile and colorless 
when pure. They are usually insoluble in water; soluble in 
alcohol, ether, bisulphide of carbon and the liquid members of 
the same group. In chemical properties they are neutral in 
reaction, and inert. Some are saturated, others unsaturated. 
Many oxidize in the air. 

Classification of Hydrocarbons. The hydrocarbons are 
classified according to their chemical composition into homo- 
logous series, as is shown in the following table: 



Classification of Hydrocarbons According to Chemical 
Composition. 1 



Methane, or Par- 
affine S e i 

C n H2n+2- 

Ethene Series, or 
define Series, 
C n H 2n . 

Ethine Series, or 
Acetylene Se- 
ries, C n H 2n — 2. 

Ethone Series, 

C n H2n— 4- 



or Par- "j 

eries, | 

2- J 



CH 4 

Methane 



Ethune 

C n H2n— 6> 



Series, 



C 2 H 6 

Ethane 



Ethene 

C 2 H 2 

Ethine, or 
Acetylene 



Propane Butane Pentane 



Propene 

C 3 H 4 

Pr opine, or 
Allylene 

(C 3 H 2 ) 

(Propone) 



C 4 H 8 

Butene 

(C 4 H 6 ) 

(Butine) 

(C 4 H 4 ) 



Pentene 



Pentine 



C 6 H 14 . 
Hexane 



C 6 H 12 . 

Hexene 

C 6 H 10 . 
Hexine 



C ft H c 



(Butone) Pentone, or Hexone, or 
Valylene Diallylene 

(C 4 H 2 ) (C 5 H 4 ) C 6 H 6 . 

Butune Pentune Hexune, or 
Dipropargyl 



THE PARAFFINE, OR METHANE SERIES OF 
HYDROCARBONS. 

The name is derived from some of the higher members of 
the series which constitute the paraffine of commerce. The 
members of this group form an homologous series, of the gen- 



eral formula C n H 



2«+ 2- 



They also form homologous series 



of derivations, as is shown below : 



1 Modification of Dr. Hoffman's classification in using Greek prefixes 
instead of Latin. 





HYDROCARBONS 


Hydrocarbon. 


Alcohol. Acid. 


CH 4 


— CH4O — CH 2 2 . 


GH 6 


— QHeO — C2H4O2. 


C 3 H 8 


— CsHsO — CaH 6 2 . 


Ctrl 10 


— GH 10 O — C 4 H 8 2 . 


C5H12 


— C5H12O — C5Hio0 2 



263 



The paraffines show a gradual increase in boiling point, 
viscidity and specific gravity with increase of molecular weight. 
The first four members of the series are gases at the ordinary 
temperature, others are liquids, while some of the higher mem- 
bers are solids. In chemical properties they are neutral, 
saturated compounds, capable of yielding substitution deriva- 
tives by replacement of hydrogen : 

CH 4 + CI2 = CH3CI + HC1. 

Most of them exist in isomeric modifications showing slight 
differences in properties, owing to a difference in molecular 
structure. The first three members are only known in one 
form, there being only one possible arrangement of the atoms 
for each, thus : 



H — C — H H — C — C — H H — C — C — C — H 



There are two possible arrangements of the atoms in the 
molecule for the fourth member, and two varieties of this com- 
pound are known, thus : 

H H H H H H H 

I I I I III 

H— C— C— C— C— H H— C— C— C— H 

I 



H 

1 


H H 

1 1 


H H H 

1 1 l 


C — H 

1 


H— C— C— H 

1 1 


1 1 1 
H— C— C— C 

1 1 1 


1 
H 


1 1 
H H 


1 1 1 
H H H 



I I I I I 

H H H H H 



Butane 



H 

H — C— H 

I 
H 

Isobutane 



264 TEXT-BOOK OF CHEMISTRY 

Three forms are possible for the fifth, and three varieties are 
known, thus : 

HHHHH HHHH 

L 1 1 I I I I I I 



H-C— C— C— C— C— H H— C— C— C— C— H 

I 
H 



I I I I II 

HHHHH H H 

Normal pentane 

H H — C— H 



I I 

H— C— H H 

Dimethyl-ethyl-methane 

H 

I 



H-C C C-H 



H — C — H 

I 
H 

Tetramethyl-methane 

In like manner, with advance in the series, there is a con- 
stant increase in the number of isomeric forms for each 
member. 

Methane, Marsh Gas, Fire Damp, CH 4 . 

Formation and Occurrence in Nature. Marsh gas is formed 
in nature during the process of decay of vegetable matter under 
water, and rises to the surface of stagnant pools. It is also 
produced in the formation of coal in the earth. The artificial 
formation of this gas is accomplished by destructive distilla- 
tion of non-nitrogenous organic matter, or by action of carbon- 
bisulphide vapors and steam on heated metallic copper. 

Properties. A clear, colorless, odorless, tasteless, com- 
bustible gas; density, .8; specific gravity, .559. Under a pres- 
sure of 140 atmospheres at o° it becomes a colorless liquid. 
When mixed with air it forms the explosive " fire damp " of 
coal mines. 

Marsh gas forms many derivatives by replacement of its 
hydrogen by other elements or groups of elements, and many 



HYDROCARBONS ' 265 

of these derivatives occur in several isomeric forms. In this 
light, marsh gas may be viewed as the parent substance of many 
thousands of organic compounds. 

The members of the parafhne series of hydrocarbons are 
formed by replacing hydrogen in each preceding member by 
the radical, CH 3 , thus : 

CH3CH3 = CsHe, vZ.2H.5CH3 = CsHs, C3H7CH3 = C4H10, &C. 

Ethane, or Dimethyl, CH 3 — CH 3 , or C 2 H 6 . Found in crude petro- 
leum and in natural gas. It is a clear, colorless, inflammable gas ; 
slightly soluble in water and alcohol. 

The artificial preparation of ethane is of interest because it shows 
the method by which the higher hydrocarbons can be formed. It can 
be formed by replacing hydrogen in marsh gas with iodine, and acting 
on the resulting compound with metallic sodium, thus : 

2CHJ + 2Na = 2NaI + C 2 H 6 . 

The formation of ethane and propane is shown in the following equa- 
tions, and is of general interest : 

(CH 3 ) 2 Zn + 2CH3I = Znl 2 + 2C 2 H 6 . 

(CH 3 ) 2 Zn + 2QH5I = Znl 2 + 2C 3 H 8 . 

Coal is derived chiefly from cellulose, and represents the 
changed remains of vegetable substances which once flourished 
on the earth's surface. When vegetable matter undergoes de- 
composition in the absence of air, in the earth, a change takes 
place which is very similar to that which occurs in destructive 
distillation. Carbon dioxide, marsh gas and water are given 
off, and the residue, rich in carbon, remains as coal. Coal con- 
sists chiefly of carbon, and besides this element it contains 
small amounts of hydrogen, oxygen, nitrogen, sulphur, and 
inorganic salts which represent the ash. As the formation of 
coal proceeds the proportionate quantity of carbon increases, 
while the hydrogen and oxygen diminish. Anthracite coal 
contains the largest percentage of carbon and represents the 
most complete change from cellulose. Bituminous coal repre- 
sents an earlier stage of formation and contains a relatively 



266 TEXT-BOOK OF CHEMISTRY 

smaller proportion of carbon, with more of hydrogen and 
oxygen, than is found in anthracite. 

Natural gas is the product of complete decomposition of 
vegetable and animal matter which has been precipitated from 
water with inorganic matter during the formation of rocks. 

Coal oil, or petroleum is the product of decomposition of 
organic matter, probably the fats of fish and other aquatic ani- 
mals, by natural destructive distillation. 

Crude petroleum is made up of a mixture of liquid paraffines 
with solid and gaseous paraffines in solution, and also contains 
hydrocarbons of other series. These hydrocarbons may be 
separated from each other by fractional distillation, advantage 
being taken of differences in the boiling point of the individual 
members. 

Crude petroleum yields a number of useful products. It is 
first refined by the addition of sulphuric acid, and it is then 
distilled at different temperatures. The hydrocarbons of low 
boiling point come over first, consisting of rhigoline, B. P. 21° ; 
benzin, or petroleum ether, B. P. 50 to- 6o°, and corresponding 
to the formula of about C 5 H 12 , C 6 H 14 ; gasoline, B. P. 75 . 

Benzin, or petroleum ether, must not be confounded with 
benzene (or benzol), the latter being an aromatic hydrocarbon 
derived from coal tar. 

Illuminating oil distills at a temperature of 150 to 250 . If 
hydrocarbons having a much lower boiling point have not been 
thoroughly removed in the distillation, they become volatilized 
when the oil is heated, and form explosive mixtures with air. 
It is on account of their presence that explosions sometimes 
occur in the use of illuminating oil. 

Mineral machine oil, liquid and solid vaseline, or "petro- 
latum," distill at temperatures approximating 300 . The lubri- 
cating oil and liquid vaseline represent different degrees of 
purity of the same substance, while vaseline represents hydro- 
carbons of higher molecular weight and boiling point. 



HYDROCARBONS - 267 

Paraffine distills at a temperature of about 350 , and con- 
sists of a mixture of the solid hydrocarbons of high molecular 
weight. 

Illuminating Gas is manufactured by destructive distillation 
of coal. It contains, when first prepared, hydrogen, methane, 
ethene, acetylene, nitrogen, ammonia, carbon monoxide, carbon 
dioxide, hydrogen sulphide, and hydrocyanic acid. The gas is 
purified by passing through water and over calcium hydroxide, 
to remove ammonia, carbon dioxide, hydrogen sulphide and 
hydrocyanic acid. 

The liquid product of the destructive distillation of coal is 
known as coal tar, and contains many useful chemicals, notably, 
benzene, aniline, toluene, and acetic acid. Other useful bodies 
found in coal tar are carbolic acid, naphthalene and paraffine. 
Coke is left as the solid residue of the distillation. 

THE OLEFINE SERIES OF HYDROCARBONS. 

General formula, C n H 2n . The hydrocarbons of the paraffine 
series are saturated compounds — i. e., they are not capable of 
forming derivatives by the addition of other elements, and only 
form them by replacement of some of the atoms in the mole- 
cule. The hydrocarbons of this series, the defines, are capable 
of forming derivatives by addition of the atoms of other ele- 
ments to the molecule and they are, therefore, known as un- 
saturated hydrocarbons. The same is true of the acetylene 
series, and of the ethone and ethnne series. 

The members of the define series are ethene, or ethylene, 
C 2 H 4 ; propene, or propylene, C 3 H 6 ; butene, or butylene, C 4 H 8 ; 
pentene, or amylene, C 5 H 10 ; hexene, or hexylene, C 6 H 12 . 

The first member of this series, methene, CH 2 , is not known, 
but the succeeding members as high as C 30 H 60 have been ob- 
tained. The structure of the members of this series is generally 
explained by assuming that the carbon atoms are temporarily 



268 TEXT-BOOK OF CHEMISTRY 

doubly linked together, thus permitting them to unite directly 
with other elements to form addition products. 

This structure is well shown in the graphic formulae : 

H H H H H 
II III 

C=C c=C— C— H 

II II 

H H H H 

Ethene Propene 

The oleHnes occur in nature associated with paraffines in 
petroleum, and are formed by destructive distillation of fats, 
waxes, coal and many other substances. They are present, 
therefore, in illuminating gas, and add greatly to the luminosity 
of the flame. 

In properties they are much like the paraffines, the first three 
being gases, C 5 H 10 a volatile liquid, and the higher members 
solids. They are usually soluble in alcohol and ether, and in- 
soluble in water. 

Ethene, or ethylene, C 2 H 4 , is present in illuminating gas. It 
combines directly with chlorine to form ethylene dichloride, 
C 2 H 4 C1 2 , an oily liquid, and for this reason is called " olefiant 
gas" (oil forming), a name which is applied to the series. 

Pentene, or Amylene, C 5 H 10 , has been used in medicine 
under the name " pentol " as an anaesthetic. The isomeric 
variety known as trimethyl-ethylene is the one used, represented 
by the graphic formula: 



H H 


H H 


\/ 


\/ 


C 


C 


H \ 

C = 


=/ H 


H / 


\ 

\ 


C 


H 



H H 



HYDROCARBONS 269 

It is formed from amylene hydrate by the action of dehydrat- 
ing agents. 

In properties it is a colorless, volatile, inflammable liquid, 
boiling at 37 to 38 C. It is soluble in chloroform, ether and 
alcohol, but insoluble in water. 

THE ACETYLENE SERIES OF HYDROCARBONS. 

These have the general formula, C M H 2M _ 2 . They are un- 
saturated hydrocarbons capable of taking up four atoms of 
univalent elements. Their structure is explained by referring 
to the graphic formula of acetylene : 

H — C = C — H. 

The first five members of this series are given in the table 
of classification of hydrocarbons. 

They are formed by destructive distillation of many organic 
bodies, and in general properties resemble the members of the 
olefine series. 

Acetylene, C 2 H 2 , is the most important of these. It is formed 
in many different ways. Thus, when alcohol, ether or aldehyde 
are passed through red-hot tubes, acetylene forms. It is also 
formed by incomplete combustion of coal gas when the flame 
of the Bunsen burner " strikes back " ; when electrical currents 
are passed between poles of carbon in an atmosphere of 
hydrogen. 

The most common method of preparation is by the action of 
calcium carbide on water, thus : 

CaC 2 + H 2 = CaO + C 2 H 2 . 

In properties it is a colorless, combustible gas, with an un- 
pleasant odor. It burns with a bright luminous flame. 

The unsaturated hydrocarbons of the general formula, C«H :B — *, 
Valylene, C 5 H 6 , and Diallylene, C 6 H 8 , have been obtained by destructive 
distillation of cannel coal and bones. 



270 TEXT-BOOK OF CHEMISTRY 

The terpines, GoHi 6 , which have the same general formula, do not 
belong in this class, for they are probably closely related to the aro- 
matic hydrocarbons. 

Of the fatty hydrocarbons in the series, CnH 2n -6, only one is known. 
This is dipropargyl, C 6 H 6 , and is of no practical interest. While the 
formula for dipropargyl corresponds to that for benzene, it must be 
remembered that the former is a fatty hydrocarbon and, therefore, en- 
tirely different from the latter, which is aromatic. 

The hydrocarbons of the benzene or aromatic series will be studied 
after we have considered the derivatives of the fatty series. 

HALOGEN DERIVATIVES OF HYDROCARBONS. 

Action of Halogens upon Saturated Hydrocarbons. The 

action in this case consists in replacement of the hydrogen of 
the hydrocarbon by the halogen atom. Chlorine and bromine 
are capable of direct action, replacing one or more atoms, and 
the action is greatly facilitated by presence of light and heat. 

Iodine does not act directly, like chlorine and bromine, but 
the iodine derivatives are obtained by the action of hydriodic 
acid upon the alcohol derivative of the hydrocarbon. Hydro- 
chloric and hydrobromic acids will also act in the same way — 

thus: 

C 2 H 5 OH + HBr = C 2 H 5 Br + H 2 0. 

Ethyl alcohol Hydrobromic acid Ethyl bromide Water 

Action of Halogens upon Unsaturated Hydrocarbons. 

This action consists in the addition of halogen atoms to the 
hydrocarbon, or in simple replacement of hydrogen, thus: 
From C 2 H 4 may be formed C 2 H 4 C1 2 , an addition derivative; 
or, C 2 H 2 C1 2 , a replacement derivative. The action of a halogen 
acid upon an unsaturated hydrocarbon is represented by the 
equation : 



C.H* 


+ HC1 = 


C 2 HbC1. 


Ethylene 


Hydrochloric 
acid 


Ethyl chloride 



General Properties of the Halogen Derivatives. Insoluble 
in water, soluble in alcohol and ether ; lower members have an 



HYDROCARBONS HALOGEX DERIVATIVES 27 1 

ethereal odor and sweet taste, and produce insensibility when 
inhaled. 

Methyl Chloride, CH 3 C1. Preparation. By heating sodium 
chloride, sulphuric acid and methyl alcohol : 

2 NaCl + H2SO4 + 2CH3OH = Na 2 S0 4 + 2H 2 + 2CH3CI. 

Sodium Sulphuric Methyl Sodium Water Methyl 

chloride acid alcohol sulphate chloride 

Properties. A colorless gas, ethereal odor, inflammable ; 
liquefied by pressure of five atmospheres to ethereal liquid. 
Used as a local anaesthetic. 

Ethyl Chloride, C 2 H 5 C1. Prepared like methyl chloride. 

Properties. A colorless, mobile, inflammable liquid, boiling 
at 12 . Used largely from glass tubes as local anaesthetic. 

Trichlor-M ethane, Chloroform, CHC1 3 . Discovered in 
1 83 1 by Liebig. 

Preparation. Can be made by the action of chlorine on 
marsh gas. Usually made by distilling a mixture of bleaching 
powder, calcium hydroxide and alcohol. The impure product 
is shaken with sulphuric acid and allowed to stand, when the 
upper layer is removed and mixed with sodium carbonate, to 
remove acid, and distilled from calcium oxide, to remove 
water. 

The chemical changes taking place are these : 



GH 6 

Ethyl alcohol 


+ Cl 2 
Chlorine 


= C2H4O 

Ethyl aldehyde 


+ 2HC1. 

Hydrochloric acid 


GH 4 

Ethyl aldehyde 


+ 3C1 2 

Chlorine 


= GHCI3O 
Chloral 


+ 3HC1. 

Hydrochloric acid 


2GHCI3O 

Chloral 


+ Ca(HO) 2 

Calcium hydroxide 


= Ca2HC0 2 

Calcium formate 


+ 2CHCI3. 
Chloroform 



Can be made also by distilling a mixture of acetone and 
bleaching powder : 

2(CH 3 ) 2 CO + 3Ca(C10) 2 = 2CHCl3 + 2Ca(OH) 2 +Ca(C 2 H 3 2 ) 2 . 

Calcium acetate 



ZJ 2 TEXT-BOOK OF CHEMISTRY 

Properties. Colorless, mobile, diffusible liquid ; ethereal odor, 
burning, sweet taste. Blisters the skin. Specific gravity, 1.476; 
boiling point, 61 °. Dissolves phosphorus, iodine, alkaloids, 
resins, fats and fatty oils. Liable to decompose by expoure to 
light with formation of chlorine and hydrochloric acid. Pres- 
ence of small quantity of alcohol acts as a preservative, and 
about one per cent, is present in the official article. Not in- 
flammable. Used as an anaesthetic. Air must be given with 
the vapor. 

Tests for Purity. 

Presence of alcohol indicated by reduced specific gravity ; of 
chlorine or hydrochloric acid, by shaking with water and 
adding silver nitrate to the latter, when white precipitate forms. 
Aldehydes indicated by brown color with caustic potash. 
Should not be colored by sulphuric acid. Should leave no 
residue upon evaporation. 

Tests for Presence. 

1. Paper moistened with chloroform and ignited gives flame 
with green mantle, and vapors of hydrochloric acid. 

2. Heated with alcoholic solution of caustic potash and 
aniline, a sickening odor is given off (benzo-isonitril). 

3. Vapors passed through red-hot glass tube decomposed into 
chlorine, carbon and hydrochloric acid. 

Tri-bromo-Methane, Bromoform, CHBr 3 . Prepared by 
adding bromine to a solution of caustic potash in methyl alcohol 
until the color no longer disappears, and purified by distilling 
from calcium chloride. 

Properties like chloroform. Specific gravity, 2.808 ; boiling 
point, 148 . Used as antispasmodic in whooping-cough. 

Tri-iodo-Methane, Iodoform, CHI 3 . Prepared by heating 
together water, ethyl alcohol, potassium carbonate and iodine 
until brown color of iodine disappears. The iodoform crystals 
deposit upon standing. 



ALCOHOLS. 273 

GH B OH + 3K 2 COs + 4I3 = CHI3 + KHC0 2 + 5KI + 2H 2 + 3C0 2 . 
Properties. Small, lemon-yellow, shining crystals, of dis- 
agreeable odor, sweetish taste. Insoluble in water, soluble in 
alcohol, ether and oils. Contains 96 per cent, of iodine. Used 
as an antiseptic. 

Test for iodoform: Odor. 

ALCOHOLS. 

Alcohols are formed by replacement of the hydrogen of 
hydrocarbons by the radical, hydroxyl (OH). They are, there- 
fore, hydroxides of hydrocarbon residues, and form series to 
correspond with the series of hydrocarbons. Alcohols are 
monatomic, diatomic, triatomic, tetratomic, &c, according to 
the number of hydrogen atoms thus replaced — one, two, three, 
four, &c. Heptatomic alcohols, those containing seven hy- 
droxyl radicals, are the highest that have been found in nature. 

Alcohols are further classed as primary, secondary and ter- 
tiary. A primary alcohol is one in which the hydroxyl is 
attached to a carbon atom which, in turn, is attached to a 
single other carbon atom. A secondary alcohol has its hydroxyl 
united with a carbon atom which is attached to two other 
carbon atoms. A tertiary alcohol has its hydroxyl united with 
a carbon atom which is attached to three other carbon atoms. 

The structure of primary, secondary and tertiary alcohols is 

represented in the following graphic formulae : 

I 
— C — 

I I II II 

— C — C — O — H. — C — C — O — H. — C — C — O — H. 

II II II 

— C— — c— 

I I 

Primary Secondary Tertiary 

The isomeric forms of hydrocarbons give isomeric alcohols. 

Occurrence in Nature. Alcohols are not found free in 
nature, but generally occur as salts with acids, in the form of 
compound ethers in fats and essential oils. 
l 9 



274 TEXT-BOOK OF CHEMISTRY 

General Methods of Preparation: 

1 . They may be formed by the action of strong alkalies upon 
compound ethers. This chemical change is referred to in a 
general way as saponification, and is represented in the 
equation : 

GHsGHsO* + KOH = GH 5 OH + KC 2 H 3 2 . 

Ethyl acetate Potassium Ethyl alcohol Potassium 

hydroxide acetate 

CH3CI + KOH = CH3OH + KC1. 

2. By the action of moist silver oxide on the chloride or bro- 
mide of the hydrocarbon residue, thus : 

C 2 H 5 C1 + AgOH = AgCl + C 2 H 5 OH. 

3. Many may be formed by fermentation, and some by de- 
structive distillation. 

General Properties. The alcohols of the lower members of 
the series are thin, volatile liquids, soluble in water ; the higher 
ones are oily, volatile liquids, but insoluble in water; while the 
highest alcohols are solid, crystalline, non-volatile and insoluble 
in water. The lower members have a burning taste and an 
aromatic odor. The highest members are odorless and taste- 
less. They are usually colorless when pure. 

Though alcohols are neutral bodies, yet the hydrogen of the 
hydroxyl may be replaced by strongly basic metals like potas- 
sium or sodium (CH 3 ONa, sodium methylate), and the oxygen 
may be replaced by sulphur. The compounds formed by re- 
placement of the oxygen of the hydroxyl of alcohols by sulphur 
are called mercaptans (from mer curio aptum, because of their 
affinity for mercuric oxide), or, more properly, hydro sulphides. 
These are formed by the action of potassium hydrosulphide 
upon the chloride of the hydrocarbon radical, thus : 

CHsCl + KHS = KC1 + CH 3 SH. 

Methyl Alcohol, Wood-Spirit, Wood-Naphtha, CH 3 OH. 



ALCOHOLS 275 

Methyl alcohol occurs in nature as methyl salicylate, or oil of 
wintergreen, in Gaultheria procumbens. 

Preparation. It is obtained by destructive distillation of 
wood. The liquid product of distillation is treated with cal- 
cium hydroxide to neutralize acetic acid, and distilled ; and the 
distillate, containing methyl alcohol, is purified by repeated dis- 
tillation. It is further purified by adding oxalic acid to form 
the crystalline oxalate of methyl, which is dried and decom- 
posed by boiling with ammonia. 

Properties. A clear, colorless, inflammable liquid, boiling 
at 66° ; specific gravity 0.812. It is miscible with wate% and 
dissolves fats, resins and camphors. It has an aromatic odor, 
a burning taste. It acts as a poison when taken internally. 

The impure methyl alcohol has a nauseous odor and taste, 
and a ten per cent, solution in ethyl alcohol is used as methylated 
spirit. 

Methyl alcohol is sometimes called carbinol, and its hydrocarbon de- 
rivatives are referred to as carbinols. (Methyl-carbinol, CH3CH2OH.) 

Ethyl Alcohol, Alcohol, C 2 H 5 OH. Occurs in nature as 
butyric ether, and in diabetic urine. 
Preparation, (a) Theoretical Methods: 

1. From ethane, by treating it with chlorine to form ethyl 
chloride, and decomposing this with caustic potash, thus : 

C 2 H 6 + Cl 2 = C 2 H 5 C1 + HC1, 
GH5CI + KOH = C 2 H 5 OH + KC1. 

2. By the action of sulphuric acid upon ethylene, and decom- 
posing the resulting etHyl-sulphuric acid with water, thus : 

C a H* + H.SO* = C 2 H 5 HS(\ 

GHbHSO* + H 2 = GH5OH + H 2 S0 4 . 

(b) Practical Method: By the alcoholic fermentation of 
sugar, in which the sugar (usually glucose) is split up into car- 



2y6 TEXT-BOOK OF CHEMISTRY 

bon dioxide and ethyl alcohol, under the influence of a ferment 
(yeast). Other alcohols, homologous with ethyl alcohol, are 
formed at the same time, as " fusel oil." The formation of 
alcohol from glucose is represented by the equation : 

C 6 H 12 6 = 2GH5OH + 2C0 2 . 

A diluted solution of glucose is allowed to ferment, and by 
repeated distillation of the liquid an alcohol containing about 
14 per cent, of water can be obtained. The remaining water 
is removed by mixing with calcium oxide, allowing to stand 
and then distilling. 

Properties. Pure alcohol is a clear, colorless, mobile, inflam- 
mable liquid, aromatic odor, and burning taste. Its boiling 
point is 78.5 °, specific gravity 0.79, and solidifies at — 130 . 
It mixes with water in all proportions with evolution of heat 
and contraction in volume. The coagulating and preservative 
action of alcohol for animal substances is largely due to its 
affinity for water. Alcohol is a solvent for many substances, 
such as fats, resins, essential oils, alkaline hydroxides, and cal- 
cium chloride. 

The presence of water in alcohol may be shown by mixing 
with benzene. This mixture shows a turbidity if the alcohol 
contain more than 3 per cent, of water ; if less, it is clear. 
Water may be removed by adding anhydrous copper sulphate, 
or heated potassium carbonate. 

"Absolute alcohol" of the U. S. P. contains not more than 
one per cent, of water ; " alcohol " contains 92.3 per cent, by 
weight, or 94.9 per cent, by volume, specific gravity 0.816 at 
1 5. 6° C. ; "diluted alcohol" is made by mixing equal volumes 
of water and alcohol. All of these are official. 

Pure alcohol acts as a poison but when diluted it is a stimu- 
lant and intoxicant, reducing the body temperature .5° to 2°. 



ALCOHOLS 277 

Tests. 

1. Dissolve crystals of iodine in alcohol and add solution of 
caustic potash until the brown color disappears. Upon stand- 
ing, crystals of iodoform will be deposited. 

2. Add sulphuric acid, heat, and then add more alcohol. 
The aromatic odor of ethyl sulphate is developed. 

3. Add a crystal of potassium dichromate and a few drops 
of sulphuric acid. Upon heating, the odor of ethyl aldehyde 
develops and the liquid turns green. 

Alcoholic Liquors are manufactured by fermentation of liquids con- 
taining a fermentable sugar, such as glucose and^ maltose. Various 
grains are used for this purpose, and in them the starch is utilized by 
converting it into maltose by germination. The grain is first caused to 
sprout, whereby diastase converts starch into the fermentable sugar 
maltose, and it is then heated to a sufficiently high temperature to stop 
further growth. From the " malted grain " an infusion is made, known 
as "wort," and this is subjected to fermentation by the action of yeast 
(chiefly Saccharomyces cerevisice). 

These liquors may be divided into the undistilled and the distilled. 

The undistilled liquors contain, besides alcohol, many non-volatile 
organic and inorganic substances, and some of these have a slight nu- 
tritive value; for example, the nitrogenous constituents of beer. Mem- 
bers of this class are: Wines, formed by fermentation of grape juice. 
Light wines, as claret, usually contain from 5 to 12 per cent, of alco- 
hol; heavy wines, as sherry and port, from 19 to 25 per cent. Beer, 
usually made by fermentation of wort of barley to which hops have 
been added, contains from 2 to 6 per cent, of alcohol. Porter and stout 
are representatives of this class containing the ■ highest per cent, of 
alcohol. 

Distilled liquors contain only volatile constituents, chiefly alcohol, 
with some ethers, compound ethers and coloring matters. They usually 
have from 47 to 55 per cent, of alcohol. 

Brandy is made by distillation of French wines. Often made from 
substitutes, however. American whiskey, made by distilling fermented 
wort of corn or rye ; Irish whiskey, from potatoes ; Scotch whiskey, 
from barley; rum, from molasses; arrack, from rice. Gin is grain spirit 
flavored with juniper berries. 

Fusel Oil is a mixture of propyl, butyl and amyl alcohols, 
CsHrOH, GH 9 OH, GHuOH. 



278 TEXT-BOOK OF CHEMISTRY 

It is formed during the fermentation of grain or potatoes in 
the manufacture of spirituous liquors, and comes over at the 
last of the distillation. 

Properties. A clear, colorless, oily liquid; penetrating, aro- 
matic odor ; burning, nauseous taste ; insoluble in water, solu- 
ble in alcohol. Amyl alcohol may be obtained from fusel oil by 
fractional distillation. It is much like fusel oil in properties, 
and is converted into valerianic acid by oxidation. 

Glycerin, C 3 H 5 (OH) 3 . Triatomic propyl alcohol. 

Occurrence in nature in the form of true fats as compound 
ethers with fatty acids. 

Prepared by the action of superheated steam or caustic 
alkalies upon fats. In the latter case the alkali combines with 
fatty acid to form soap, and glycerin is set free, thus : 

C3H 5 (C 18 H3 2 2 ) 3 + 3KOH = 3KC 18 H 32 2 + GH E (OH) 3 . 

Olein Caustic potash Potassium Glycerin 

oleate, soap 

Properties. A clear, colorless, thick, sweet liquid; hygro- 
scopic ; soluble in water and alcohol ; specific gravity, 1.246. It 
cannot be volatilized without decomposition, but can be dis- 
tilled when heated with water or in presence of steam. Gly- 
cerin is a good solvent for many organic and inorganic bodies. 
It forms glycerites. Boroglycerin, C 3 H 5 B0 3 , a compound of 
glycerin with boric acid. 

Tests. 

1. Should not turn dark with sulphuric acid, and when the 
mixture is heated gives the irritating odor of acrolein. 

2. Should give no red color with Fehling's solution ; absence 
of glucose. 

3. Heated on platinum foil, should burn without residue. 

4. Imparts green color to flame from borax bead. 

ALDEHYDES. 

Aldehydes contain the radical, HCO, in combination with 
hydrocarbon residues, thus: 



ALDEHYDES * 279 

H H 

I I 

H — C — C 

I II 
H O 

Ethyl aldehyde 

Aldehydes are formed by incomplete oxidation of primary 
alcohols, whereby hydrogen is removed ; further oxidation 
would result in the formation of an acid, thus : 

GH 6 + O = H 2 + C2H4O, 

Ethyl alcohol Oxygen Water Ethyl aldehyde 

C 2 H 4 + O ' " = C 2 HX> 2 . 

Ethyl aldehyde Oxygen Acetic acid 

The name of the aldehyde is derived from the alcohol whence 
it comes, and also from the acid it would form by further oxida- 
tion, thus : Ethyl alcohol when oxidized forms an aldehyde, 
and this aldehyde by further oxidation forms acetic acid; the 
name of the aldehyde, in this case, is ethyl aldehyde, or acetic 
aldehyde. Few of the aldehydes have more than scientific in- 
terest. Formic aldehyde and acetic aldehyde are the ones used 
in medicine. 

Formic Aldehyde, Formaldehyde, Methyl Aldehyde, CH 2 0, 
(H.CHO) is prepared by passing the vapors of methyl alcohol 
and air over heated spiral of copper or platinum and carefully 
condensing. This method of preparation gives a mixture of 
aldehyde and alcohol. 

Formic aldehyde may be obtained pure by heating dry cal- 
cium formate, as shown in the following equation : 
Ca(HC0 2 ) 2 = CH 2 + CaCOs. 

Calcium formate Formic aldehyde Calcium carbonate 

Properties. Formic aldehyde is a clear, colorless gas, having 
a pungent odor, and condensible to a liquid which boils at 
— 21 . It is soluble in water or alcohol, and is used ex- 
tensively as a disinfectant and antiseptic. 

Solution of Formaldehyde, U. S. P., is " an aqueous solu- 
tion, containing not less than 37 per cent., by weight, of abso- 
lute formaldehyde." 



280 TEXT-BOOK OF CHEMISTRY 

Paraformaldehyde, C 3 H 6 3 , is a polymeric form of methyl 
aldehyde. When a solution of formic aldehyde in methyl 
alcohol is slowly evaporated, paraformaldehyde separates in 
crystals. Paraformaldehyde is largely used as a disinfectant 
by heating, to convert it into' gaseous formic aldehyde. 

Acetic Aldehyde, Ethyl Aldehyde, C 2 H 4 0. (CH 3 CHO.) 
Prepared by oxidation of ethyl alcohol by dichromate of potash 
and sulphuric acid and distilling. 

Properties. Neutral, colorless liquid ; strong, peculiar odor ; 
miscible with water and alcohol; boiling point 21 °. Strong 
tendency to unite with other bodies — hydrogen to form alcohol, 
oxygen to form acetic acid. Molecules unite with each other 
to form polymeric modification. A strong reducing agent. 

Paraldehyde, C 6 H 12 3 . A polymeric modification of the 
above. Produced by adding a few drops of sulphuric acid to 
ethyl aldehyde. 

Properties. A solid, crystalline mass below 10.5 ° ; a clear, 
colorless liquid above that point; peculiar odor, disagreeable 
taste, soluble in 8.5 parts water, boils at 124 . Used as hyp- 
notic in elixir of paraldehyde. 

Trichloraldehyde, Chloral, C 2 HCl s O. (CCl 3 .CHO.) This 
compound is formed by replacement of three hydrogen atoms 
in ethyl aldehyde by chlorine. 

Preparation. By passing a stream of dry chlorine gas 
through ethyl alcohol to saturation. The liquid to be kept cool 
at first and gradually heated to the boiling point as the opera- 
tion proceeds. Separates into two layers; the lower layer re- 
moved, shaken with sulphuric acid, distilled and mixed with 
calcium oxide and again distilled; that coming over between 
94 and 99% collected. Chemical changes represented in the 
equation : 

C 2 H 6 + Cl 2 = GH^O + 2HCI. 

C2H4O + 3C1 2 = GHClsO + 3HCI. 



ALDEHYDES 28 1 

Properties. A clear, colorless, oily liquid ; acrid odor and 
caustic taste; specific gravity 1.5, boiling point 95 . 

Chloral Hydrate (U. S. P.), C 2 HC1 3 0.H 2 0. Prepared by 
adding water to chloral. 

Properties. Colorless, crystalline solid, aromatic, agreeable 
odor, pungent taste, freely soluble in all the common solvents. 
Forms a liquid when mixed with camphor or carbolic acid; 
it melts at 58 . 

Tests. 

1. Heated with caustic potash gives odor of chloroform: 

C2HCI3O + KOH = KHC0 2 + CHCla. 

Chloral Potassium Chloroform 

formate 

2. Heated with silver nitrate and ammonia water gives silver 
mirror. 

Sulphur Derivatives of Alcohols. Mercaptans, or hydrocarbon hydro- 
sulphides are formed by replacement of oxygen of the hydroxyl of alco- 
hols by sulphur (C2H5HS). These compounds when oxidized form 
acids, known as sulphonic acids. Thus : When ethyl hydrosulphide, 
C2H5HS, is acted on with nitric acid, it forms ethylsulphonic acid, 
C2H5HSO3, by union with three oxygen atoms. The radical of this 
acid is C2H5SO2, known as ethylsulphonyl, and can replace hydrogen in 
hydrocarbons to unite with the basic residue. 

Sulphonal, C(CH 3 ) 2 (C 2 H 5 S02) 2 , is a compound formed by replace- 
ment of two hydrogen atoms of marsh gas by the radical ethylsul- 
phonyl, and the two remaining hydrogen atoms by the radical methyl, 
CH 3 . Its chemical name would therefore be dimethyl-diethylsulphonyl- 
methane. 

Prepared by action of ethyl-mercaptan upon dimethyl-ketone, thus : 

(CH 3 ) 2 CO + 2C2H5SH = (CH3) 2 C(C 2 H 5 S)2 + H2O, 
the product is then oxidized by potassium permanganate, thus : 
(CH 3 ) 2 C(C 2 H 5 S) 2 + 20 2 = (CH 3 )2C(C 2 H 5 S0 2 )2. 

Sulphonal 

Properties. Colorless, odorless, tasteless crystals ; soluble in 20 parts 
hot water, 100 parts cold water; soluble in ether, chloroform and ben- 
zene. 



282 TEXT-BOOK OF CHEMISTRY 

Trional, Diethylsulphonyl-methyl-ethyl-methane, CH 3 C 2 H 5 C(C2H B - 
S0 2 ) 2 . Made by the action of ethyl mercaptan on methyl-ethyl-ketone. 

Properties. Colorless, lustrous, odorless crystals, soluble in hot 
water, alcohol and ether. 

Tetronal, (C2H 5 )2C(C 2 H 5 S02)2. A similar compound in chemical 
and therapeutic nature. 

KETONES. 

Ketones are compounds formed by replacement of hydrogen 
in hydrocarbons by the bivalent radical, CO, or carbonyl. 

By oxidation of primary alcohols aldehydes are formed. A 
primary alcohol containing the radical, — CH 2 OH, when oxi- 
dized has two of its hydrogen atoms removed and becomes 

— COH ; while on the other hand a secondary alcohol containing 
I 
CH.OH, when oxidized, loses two hydrogen atoms, and be- 

I 
comes > CO, the radical characteristic of ketones. 

The aldehydes represent bodies which result from the in- 
complete oxidation of primary alcohols, and further oxidation 
forms the corresponding acid ; while ketones represent the first 
products of oxidation of secondary alcohols, any further oxida- 
tion resulting in the decomposition of the molecule, thus : 
GHX) + O = C 2 H 4 2 . 
(CH 3 ) 2 CO + 3 = C2BLO2 + C0 2 + H 2 0. 

Ketones are not affected by weak oxidizing agents, but re- 
quire for their oxidation the more powerful ones, like chromic 
acid. 

Dimethyl Ketone, Acetone, (CH 3 ) 2 CO, is found in small 
amount in the blood, in the urine and secretions. The amount 
in the urine is increased in diabetes mellitus. 

Formed by the distillation of sugar, gums and cellulose. 

Preparation. By the dry distillation of calcium acetate : 
Ca(C 2 H 3 2 )2= CH3CH3CO + CaC0 3 . 

Properties. A clear, colorless liquid, of agreeable ethereal 
odor ; soluble in water, ether and alcohol. Sodium amalgam 



ORGANIC ACIDS ' 283 

reduces it to isopropyl alcohol, from which it may be said to 
be theoretically derived. 

H 
I 
H O 

I I 
H — C C H or C3H7OH, Isopropyl alcohol. 

H I 

H — C — H 
I 
H 

By removal of two atoms of hydrogen from the above, we 

have: 

H O 

■ I II 
H — C — C 
I 

H or CH3COCH3, Acetone. 

H-C-H 
I 
K 

Acetone is used as a solvent for resins, and for the manu- 
facture of chloroform. 

ORGANIC ACIDS. 

Definition and Constitution. Compounds formed by re- 
placement of hydrogen of hydrocarbons by the radical car- 
boxyl, HC0 2 . The acids are monobasic, dibasic and tribasic, 
&c, according to the number of hydrogen atoms so replaced 
— one, two, three, &c. 

Carboxyl contains the replaceable hydrogen of the acid, and 
consists of hydroxyl, OH, and carbonyl, CO. Its structure is 
represented by the graphic formula : 



'1 

O J 



Hydroxyl. 



I 
C 

|| \ Carbonyl. 
O 

Carboxyl 



284 TEXT-BOOK OF CHEMISTRY 

The organic acids form homologous series corresponding to 
the series of hydrocarbons from which they are derived. 

Occurrence in Nature. Organic acids usually occur in 
vegetable and animal tissues in combination with bases, or in a 
free state. They are often found combined with metals in the 
form of salts, and they sometimes occur with alcohol radicals 
as compound ethers. 

Many of these acids are found free, such as citric acid, in 
lemon juice ; tartaric acid, in the grape and strawberry ; oxalic 
acid, in sorrel; formic acid, in ants; and uric acid, in the 
flesh-eating animal. 
Formation : 

1. By oxidation of alcohols, forming first the aldehyde and 
then the acid. 

2. By the action of alkalies on compound ethers to form an 
alkaline salt of the acid, and then decomposing the salt with 
a stronger acid. 

3. By destructive distillation. 

4. By fermentation. 

General Properties. They have the properties of inorganic 
acids as regards taste, reaction and formation of salts ; but in 
the higher members of the series these properties gradually 
disappear. The lower members of the series are usually color- 
less liquids of considerable odor, taste, acid reaction and fre- 
quently volatile. The higher members become solids without 
odor, taste, volatility or acid character. 

The oxygen of the organic acid is capable of being replaced 
by sulphur in many cases, and the result of this reaction is the 
formation of a compound known as a thio-acid, in reference to 
the sulphur atom. An example of this sort of change can be 
found in the case of acetic acid, whose chemical formula is 
C 2 H 4 2 . When a part of the oxygen is replaced in this acid 
by sulphur we have an acid whose name is thio-acetic acid, 
and whose formula is C 2 H 4 OS. 






GENERAL CONSIDERATIONS 285 

The Anhydride of an organic acid is formed by removal of 
one molecule of water from two molecules of the acid, thus : 

2GHA-E0 = (GH 3 0) 2 + H 2 0. 

The radical of an organic acid may be viewed as that which 
is left after removal of OH, the acid being an hydroxide of 
this radical, and the anhydride being an oxide. 

1. Monobasic Fatty Acids, General Formula, GtH 2 »0 2 . 
Formed from primary monatomic alcohols by oxidation. 

Formic Acid, H.HCOo. Found in nature in ants, stinging 
nettle and fir cones. 

Preparation, As sodium formate, by action of moist carbon 
monoxide on dry sodium hydroxide at 200 : 
CO + NaOH = NaHC0 2 . 

By oxidation of methyl alcohol. By heating oxalic acid with 
glycerine, thus : 

C 3 H 5 (OH) 3 + H2GO4 = C 3 H 5 (OH) 2 HC0 2 + C0 2 + H 2 0. 

C 3 H 5 (OH) 2 HC0 2 + H 2 = C 3 H 5 (OH) 3 + H 2 C0 2 . 

Properties. A clear, colorless liquid, penetrating odor, 
strongly acid. It is a strong reducing agent, and unites with 
inorganic bases to form salts. These formates are soluble, ex- 
cept the lead and mercurous salts. The acid, when diluted, 
acts as a powerful antiseptic ; but when concentrated, produces 
painful blisters on the skin. 

Acetic Acid, H.C 2 H 3 2 . Known to the Ancients as vine- 
gar ; to the Alchemists in a purer and more concentrated form. 

Occurrence in Nature. Partly free and partly combined 
with potassium and calcium in plant juices and in perspiration. 

Preparation. By oxidation of alcohol and by destructive 
distillation of wood. 

Formed from alcohol by pouring diluted spirit over shavings 
contained in open casks with holes in the sides for free circu- 



286 TEXT-BOOK OF CHEMISTRY 

lation of air. The acetic ferment, " mother of vinegar," facili- 
tates the oxidation. 

Formed from wood by taking the liquid product of destruc- 
tive distillation, neutralizing with milk of lime, and to the re- 
sulting calcium acetate dilute sulphuric acid is added, when the 
liberated acetic acid is distilled off. Called pyroligneous acid 
when obtained from this source, and impure. 

Properties. When pure, a strongly acid liquid; pungent 
odor; blisters the skin; solid below 15 ; boils at 118 ; specific 
gravity, 1.056; miscible with water, alcohol and ether; forms 
acetates. The pure acid known as glacial acetic acid. Acetic 
acid U. S. P. contains 36 per cent., and diluted acetic acid con- 
tains 6 per cent. 

The specific gravity of acetic acid cannot be used to deter- 
mine its strength, since an acid containing 78 per cent, has the 
highest, 1.074, and an addition of either water or acetic acid 
will lower the specific gravity. 

Ammonium Acetate, NH 4 C 2 H 3 2 . Generally used in so- 
lution as " Spirit of Mindereris," which is made by saturating 
dilute acetic acid with ammonium carbonate. 

Ferric Acetate, Fe 2 (C 2 H 3 2 ) 6 . Made by dissolving ferric 
hydroxide in acetic acid, and used in solution as liquor ferri 
acetatis. A reddish-brown liquid. 

Potassium Acetate, KC 2 H 3 2 ; Sodium Acetate, NaC 2 - 
H 3 2 .3H 2 0; Zinc Acetate, Zn(C 2 H 3 2 ) 2 .2H 2 0: Made by 
dissolving the carbonates of the metals in acetic acid and 
crystallizing. All three, white soluble salts. 

Lead Acetate, Pb(C 2 H 3 2 ) 2 .3H 2 0. Sugar of lead. Made 
by dissolving lead oxide in diluted acetic acid and crystallizing. 

Properties. Shining, transparent, colorless crystals ; sweet- 
ish, astringent, metallic taste. Soluble in water and to some 
extent in alcohol ; efflorescent in dry air and absorbs carbon 
dioxide by exposure. Turbidity of solution due to presence of 



ORGANIC ACIDS 287 

oxide in the salt which forms carbonate with carbonic acid of 
impure water, or due to presence of carbonate in the salt; 
cleared by addition of acetic acid. 

Goulard's Extract, solution of subacetate of lead. Made by 
boiling a mixture of lead acetate and oxide with water, when 
a basic, or sub-acetate (Pb(C 2 H 3 2 )2PbO) is formed, and 
enters into solution. Contains 25 per cent. Diluted lead water 
contains 1 per cent. 

Cupric Acetate, Cu(C 2 H 3 2 ) 2 .H 2 0. Made by dissolving 
copper carbonate in acetic acid and crystallizing. 

Properties. Green, prismatic crystals, soluble in water. 
Verdigris is a basic cupric acetate, Cu(C 2 H 3 2 ) 2 CuO, made by 
the action of dilute acetic acid and air on metallic copper. 
Paris green is an impure cupric aceto-arsenite, made by boiling 
verdigris with arsenous oxide. 

Tests for Acetates. 

1. Neutral solutions of acetates turn deep-red on adding 
ferric chloride. 

2. Acetates heated with sulphuric acid give odor of acetic 
acid. 

3. Heated with sulphuric acid and ethyl alcohol, give odor 
of acetic ether. 

Butyric Acid, H.C 4 H 7 2 . Normal butyric acid found in 
combination with glycerine in butter, also in cod liver oil and 
croton oil. Found free in rancid butter, sweat, and cheese. 
Formed by fermentation of lactic acid, or of albumenoids. 

Properties. Colorless liquid, disagreeable, rancid odor, 
soluble in water, boiling at 163 . 

Valerianic Acid, H.C 5 H 9 2 . Found in valerian and an- 
gelica root. Prepared by oxidation of amyl alcohol, by sul- 
phuric acid and potassium bichromate: 

C5H11OH + 2 = C 5 H 10 O 2 + H 2 0. 



288 TEXT-BOOK OF CHEMISTRY 

Properties. Colorless, oily liquid, strong, disagreeable odor ; 
boils at 1 75 ; soluble in alcohol, slightly soluble in water. 
Forms valerianates. 

Valerianate of ammonium, of zinc, of quinine and of iron are 
used in medicine. These are white salts, except the iron valeria- 
nate, which is brown. Ammonium valerianate is soluble in 
water ; the others insoluble. 

Caproic acid, H.C 6 Hii0 2 , and Caprylic acid, H.C 8 Hi 5 02, the next 
members of the series, are found in butter. Made from goat's milk 
(whence the name), cheese and cocoanut oil. 

Other acids of the series are: Pelargonic acid, H.C 9 Hi 7 2 ; of Pelar- 
gonium roseum; Laurie acid, H.G2H23O2, of spermaceti; Myristic acid, 
H.C14H28O2, of butter and spermaceti. 

Palmitic Acid, HC 16 H 31 2 . Found in solid fats in combina- 
tion with glyceryl as palmitin. Forms a white insoluble solid, 
fusing at 60 °. 

Margaric Acid, H.G7H33O2. Formerly supposed to be present in nat- 
ural fats. Made only by synthetic means. 

Stearic Acid, H.C 18 H 35 2 . Occurs in natural fats in com- 
bination with glyceryl as stearin. Properties. Hard, white, 
odorless, tasteless solid ; insoluble in water, soluble in hot alco- 
hol and ether; melts at 69.2 °. 

2. Monobasic Fatty Acids, General Formula, CnH 2w -20 2 . 

These acids are derivatives of the olefine or unsaturated hy- 
drocarbons. The lowest members are only obtained synthetic- 
ally ; the higher ones are found in animal and vegetable fats. 
The only member of this series of any practical interest is oleic 
acid. 

Oleic Acid, H.C 18 H 33 2 . Occurs in nature as oleate of 
glyceryl, or olein, in natural liquid fats. Prepared by boiling 
olive oil with caustic potash, to form potassium oleate, and 
liberating the oleic acid from this salt by action of tartaric acid. 

Properties. Colorless, odorless, tasteless, neutral liquid; 



ORGANIC ACIDS 289 

forms crystals when cooled to near o° ; insoluble in water, but 
soluble in other common solvents ; turns brown by exposure. 
Specific gravity of oleic acid is 0.895. 

This acid forms oleates with basic substances, some of which 
are used in medicine — oleate of mercury, lead, veratrine, zinc. 
3. Monobasic Fatty Acids, General Formula, C»H 2 »_40 2 . 

The acids of this series correspond to the acetylene series of 
hydrocarbons. In this group is found: 

Linoleic Acid, H.C 18 H 31 2 . Found in combination with 
glyceryl in linseed oil. 

Properties. A yellow liquid, which rapidly solidifies in air. 

Organic Acids Derived from Diatomic and Higher Alcohols. 

In formation of acids by oxidation of alcohols containing 
more than one hydroxyl radical, sometimes only a part of the 
hydroxyl is changed into an acid radical, and the resulting com- 
pound partakes of the nature of an alcohol, as well as an acid, 
because of the remaining alcoholic hydroxyl. For example, the 
diatomic alcohol, ethylene glycol, HOH 2 C — CH 2 OH, may be 
oxidized into glycollic acid, HOH 2 C — COOH. This acid is 
said to be diatomic ; referring to the number of hydroxyl groups, 
and monobasic ; referring to the number of carboxyls. Its 
graphic formula is shown below. 

Glycollic Acid, C 2 H 4 3 . A monobasic, diatomic acid. Same 

formula as acetic, except that it contains OH in place of H. 

Thus: 

H H 

I I 

O 

1 I 

H — C — C Hydroxy-acetic acid. 

I I! 

H O 

Partakes of the nature of an alcohol and an acid because 
of alcoholic hydroxyl. 

Found in unripe grapes and leaves of wild vine. 
20 



29° TEXT-BOOK OF CHEMISTRY 

Properties. Colorless needles, soluble in water, alcohol and 
ether. 

Lactic Acid, HC 3 H 5 3 , or C 2 H 4 (OH)COOH. Occurs in 
nature in plant juices, in sauerkraut, gastric juice and gray 
matter of brain. 

Produced by the " lactic fermentation of sugar." 

Prepared by mixing sugar, in solution, with putrid cheese, 
milk and chalk, and digesting for several weeks at temperature 
of 30 °. The resulting calcium lactate purified by crystalliza- 
tion, and decomposed by oxalic acid. 

Properties. Official acid has 75 per cent, of pure acid; a 
colorless, syrupy liquid, odorless, of acid taste; specific gravity 
1.206. It absorbs moisture from the air, and is soluble in 
water, alcohol and ether. Sarcolactic acid is a form of lactic 
acid found in muscle tissues. 

Ferrous Lactate, Fe(C 3 H 5 3 ) 2 .3H 2 0. Made by dissolving 
iron, as filings, in lactic acid. 

Pale, greenish-white crusts, or needle-shaped crystals ; pecu- 
liar odor, sweetish taste, soluble in water. 

Strontium Lactate, Sr(C 3 H 5 3 ) 2 .3H 2 0. Made by dissolv- 
ing strontium carbonate in lactic acid. A white, granular, crys- 
talline powder ; bitter, saline taste ; soluble in water. 

Oxalic Acid, H 2 C 2 4 .2H 2 0. In chemical structure this acid 
consists of two carboxyl groups linked together ; it is diatomic 
and dibasic. 

Occurrence in Nature in many plants as potassium or calcium 
salt. Produced by oxidation of many organic bodies by nitric 
acid ; as sugar, starch, cellulose, &c. 

Preparation. By heating sawdust and caustic potash to 250 , 
dissolving the resulting potassium oxalate in water, adding 
calcium hydroxide and decomposing the precipitated calcium 
oxalate with sulphuric acid. 

Properties. The acid crystallizes in large, prismatic crystals, 






ORGANIC ACIDS 



29I 



with 2 molecules of water, and is soluble in water and alcohol. 
It as a strong reducing agent, decolorizes solution of potassium 
permanganate, and acts as a poison. Antidote: A salt of cal- 
cium. 

Cerium Oxalate, Ce 2 (C 2 4 ) 3 .9H 2 0, is used in medicine as a 
white, insoluble, granular, tasteless powder. 

Salt of Sorrel is the acid potassium oxalate, or this compound in 
union with oxalic acid. It is used to remove ink-stains and to bleach 
straw, and is poisonous like oxalic acid. 

Tests for Oxalates. 

1. Heated with sulphuric acid they give off CO and C0 2 . 

2. Silver nitrate gives white precipitate of silver oxalate. 

3. Neutral solutions with calcium chloride give white pre- 
cipitate, insoluble in acetic, soluble in hydrochloric acid. 

Malic Acid, H 2 QH 4 5 , or CH 2 .CHOH(COOH) 2 . A dibasic, tria- 
tomic acid, found extensively in the vegetable kingdom in unripe apples, 
quinces, grapes, &c. It forms deliquescent, needle-shaped crystals, sol- 
uble in water and alcohol. 

Tartaric Acid, H 2 C 4 H 4 6 , or (CHOH) 2 (COOH) 2 . A di- 
basic, tetratomic acid. This acid occurs in four stereo-isomeric 
varieties. Dextro-tartaric acid turns the plane of polarized 
light to the right, and is the usual form of the acid. 

Occurrence in Nature. Partly free and partly in combina- 
tion with calcium and potassium in the juices of fruits. x\bund- 
ant in grape juice as potassium acid tartrate, which is deposited 
in wine casks as " argol " during fermentation. 

Preparation. By acting on argol with calcium carbonate and 
then calcium chloride, to form calcium tartrate, and decom- 
posing this salt with sulphuric acid, to form calcium sulphate 
and tartaric acid; the latter is then crystallized from solution. 
The chemical changes are represented by the equations : 

2KHGH*0 6 + CaCOs = CaC*H 4 Oa + K,GH*0. + H 2 + C0 2 , 
K-GH4O6 + CaCl 2 = CaGH 4 0« -j- 2KCL 



292 TEXT-BOOK OF CHEMISTRY 

Properties. Colorless, transparent, prismatic crystals, or 
white powder; agreeable, sour taste; soluble in water and 
alcohol; melts at 135 . 

Potassium Bitartrate, KHC 4 H 4 O e . (Cream of tartar.) 

Prepared by purification of argol by recrystallizing-. 

Properties. White powder or crystals, agreeable acid taste, 
slightly soluble in cold water and alcohol; freely soluble in 
hot water. 

Formation of normal tartrate by action of potassium bicar- 
bonate on this salt is shown in the equation : 

KHC4H4O6 + KHCOs = K 2 CH 4 6 + H 2 + C0 2 . 

Potassium Sodium Tartrate, Rochelle salt, KNaC 4 H 4 - 
6 4H 2 0. Prepared by neutralizing solution of potassium bi- 
tartrate with sodium carbonate, and crystallizing. 

Properties. A white powder, or colorless transparent crys- 
tals, of cooling, saline taste, soluble in water. 

Seidlitz pozvders contain this salt. They are made by wrap- 
ping 120 grains Rochelle salt and 40 grains sodium bicarbonate 
in a blue paper, and 35 grains tartaric acid in a white paper ; 
to be given in solution while effervescing. 

Antimony and Potassium Tartrate, Tartar emetic, [K- 
(SbO)C 4 H 4 6 ] 2 H 2 0. Prepared by dissolving freshly precipi- 
tated antimonous oxide in solution of potassium bitartrate and 
crystallizing. The reaction is represented thus : 

2KHC4H4O6 + Sb 2 3 = 2K(SbO) GELOe + H 2 0. 

Properties. Colorless, rhombic crystals ; nauseous, metallic 
taste ; soluble in water ; insoluble in alcohol ; poisonous. Anti- 
dote, tannic acid. 

Iron and Ammonium Tartrate and Iron and Potassium 
Tartrate are made by mixing solution of ferric chloride with 
tartaric acid and adding ammonia water, or solution of caustic 
potash, as the case may be. Double compounds are thus 



ORGANIC ACIDS 



293 



formed, which do not crystallize, but are obtained in the form 
of scales by evaporating to a syrupy consistency and spreading 
on glass plates to dry. In this way many of the scale com- 
pounds of the U. S. P. are obtained. In some cases the 
metallic hydroxide is precipitated, dissolved in the organic acid 
and scaled, as described. 

Tests for Tartrates. 

1. Neutral solutions when heated with calcium chloride give 
a white precipitate, soluble in caustic potash. Calcium citrate 
is insoluble. 

2. Nitrate of silver gives a white precipitate, which blackens 
on boiling. 

3. Heat chars the acid, giving an odor of burnt sugar. 

4. Sulphuric acid chars. 

Levo-tartaric acid is like dextro-tartaric acid, except that it 
turns the plane of polarized light to the left. 

Racemic acid forms when equal quantities of dextro- and 
levo-tartaric acid are mixed in solution. It is optically inactive. 

Meso-tartaric acid is an optically inactive tartaric acid, which 
cannot be decomposed into dextro- and levo-tartaric acid like 
racemic acid. 

Citric Acid, H 3 C 6 H 5 7 , or C 3 H 4 (OH) (COOH) 3 . A tri- 
basic tetratomic acid. Occurs in nature in the free state in 
lemons, oranges and other fruits ; as calcium citrate in potatoes, 
beets and wood. 

Preparation. By action of calcium carbonate on lemon juice, 
decomposition of the resulting calcium citrate by sulphuric acid, 
and crystallizing. 

Properties. Clear, colorless, prismatic crystals, containing 
one molecule water of crystallization; agreeable, acid taste; 
soluble in water and alcohol, loses water at 135 and melts at 
i53°- 



294 TEXT-BOOK OF CHEMISTRY 

The citrates commonly used are made by dissolving carbon- 
ates in solution of citric acid. Effervescent citrates are dry 
mixtures of potassium bicarbonate, or other carbonates, and 
citric acid. 

Tests for Citrates. 

The official metallic citrates are : 

Potassium Citrate, K 3 C 6 H 5 7 .H 2 0. Forms colorless crys- 
tals, or white, granular powder; soluble in water, of cooling, 
saline taste. 

Lithium Citrate, Li 3 C 6 H 5 7 . Forms a white powder ; odor- 
less, with a cooling, faintly-alkaline taste ; deliquescent ; soluble. 

Bismuth Citrate, BiC 6 H 5 7 . Forms a white, amorphous or 
faintly crystalline powder ; odorless, tasteless, and permanent 
in air. Made by boiling a solution of citric acid with bismuth 
nitrate, when it forms as a white powder; insoluble in water, 
soluble in ammonia water. 

Bismuth and Ammonium Citrate, a scale compound. Made 
by dissolving the bismuth citrate in ammonia water, and evapo- 
rating at a low temperature and scaling. 

Ferric Citrate. Made by dissolving ferric hydroxide in cit- 
ric acid, and evaporating to syrup, and pouring in thin layer 
on slabs to dry in scales. 

Citrates of Iron and Ammonium, Strychnine, Quinine and 
soluble ferric phosphate are made by mixing ferric citrate with 
the compounds named, and, in the last case, with sodium phos- 
phate, and scaling. 

The effervescent solution of magnesium citrate, made by dis- 
solving magnesium carbonate in excess of citric acid, adding 
syrup, flavoring, and adding about 40 grains of potassium 
bicarbonate, and quickly sealing in a strong bottle. 

1. Neutral solutions boiled with calcium chloride give a 
white precipitate. 

2. Neutral solutions with silver nitrate give a white precipi- 






ETHERS AND ESTERS * 295 

tate, which does not blacken on boiling. Different from tar- 
trates. 

3. Alkaline solutions turn green, or reddish-green, with 
potassium permanganate. 

ETHERS AND COMPOUND ETHERS, OR ESTERS. 
Chemical Constitution. Ethers are formed by replace- 
ment of the hydrogen of the hydroxyl of alcohols by hydro- 
carbon residues and, therefore, may be said to be oxides of 
hydrocarbon radicals. The hydrocarbon radicals may be of 
the same kind, when a simple ether is formed, or they may be 
of different kinds, forming a mixed or double ether : 

C 2 H 5 C 2 H 5 0. GH5CH3O. 

Simple ether Mixed or double ether 

The ethers may also be considered as the anhydrides of alcohols, 

thus: 

2GH 5 OH = (GH 5 ) 2 + H 2 0. 

Compound Ethers, or Esters, are formed by replacement of 
the replaceable hydrogen of acids by hydrocarbon residues, and 
are viewed as salts, thus : 

(GH 5 )(C 2 Ha0 2 ). 

Ethyl acetate 

Ethers and compound ethers may be formed, from monatomic, 
diatomic, triatomic or higher alcohols, and from monobasic, 
dibasic or higher acids ; thus giving the possibility of formation 
of a great number and variety. 

General Methods of Preparation, i. By the action of the 
bromide or iodide of a hydrocarbon radical upon potassium or 
sodium alcoholate : 

CH3I + CHaONa — Nal -f (CH 3 ) 2 0. 

Methyl Sodium Sodium Methyl 

iodide methylate iodide ether 



296 TEXT-BOOK OF CHEMISTRY 

2. By the action of sulphuric acid upon alcohols ; thus re- 
moving water: 

2C2H5OH + H 2 S04 =. (C 2 H 5 ) 2 + H.SO* + H 2 0. 

3. By the action of hydrocarbon chlorides or iodides upon 
salts : 

C 2 H 5 I + KGH3O2 = KI + C 2 H 5 C 2 H 3 2 . 

4. By union of alcohols with acids : 

CH3OH + HC 2 H 3 2 = CH 3 C 2 H 3 2 + H 2 0. 

Occurrence in Nature. In plants and animals in the form 
of fats and fatty oils ; in plants, as essential oils ; in spermaceti 
and wax. 

General Properties. Lower members, usually volatile 
liquids, of peculiar aromatic, agreeable odor. They become less 
volatile and less fluid as they advance in the series, until they 
finally become solid non-volatile bodies. They are neutral and 
the compound ethers are saponifiable by the action of alkalies. 

Methyl Ether (CH 3 ) 2 0. Made by action of sulphuric acid 
on methyl alcohol. 

Properties. A gas at ordinary temperature. Liquefied by 
pressure to a mobile, colorless, inflammable liquid. 

Ethyl Ether, Ether (C 2 H 5 ) 2 0. (Sulphuric ether.) Prepa- 
ration. By heating in a retort to 140 , ethyl alcohol and sul- 
phuric acid, having the apparatus so arranged that more alcohol 
may be added from time to time, and condensing the vapors in 
a cooled receiver. The distillate is then mixed with calcium 
oxide and chloride and redistilled. The chemical changes are 
represented in the equations : 

GHbOH + H 2 SO, == GHbHSO* + H 2 0, 

Ethyl alcohol Sulphuric acid Ethyl-sulphuric acid Water 

GHbHSO* + C 2 H 5 OH = (C 2 H 5 ) 2 + H 2 S0 4 . 

Ethyl-sulphuric acid Ethyl alcohol Ethyl ether Sulphuric acid 

The power of sulphuric acid to convert an unlimited amount 
of alcohol into ether, as this equation would indicate, is not 



ETHERS AND ESTERS 2^J 

strictly true, because of the side reactions ; some of the acid 
being deoxidized by carbonization of impurities in alcohol, and 
some being rendered inert by dilution with water, etc. 

Properties. A clear, colorless, mobile, volatile, inflammable 
liquid ; soluble in ten parts of water, in alcohol, chloroform, ben- 
zene and oils; specific gravity about 0.716, boiling point 35.5 °. 
It causes intoxication and insensibility when inhaled, and the 
vapor is given by inhalation, without air, because of the oxygen 
it contains. Official ether contains 96 per cent, ether, 4 per 
cent, alcohol. The anhydrous ether is obtained by distilling 
from metallic sodium. Ether vapor forms an explosive mixture 
with air. Ether dissolves oils, fats, resins, bromine, iodine, 
phosphorus and many salts. 

Spirit of ether is a mixture of one part ether and two parts 
alcohol. Compound spirit of ether, or Hoffmann's anodyne 
contains, in addition to the above, ethereal oils. 

Methyl-Ethyl Ether, CH 3 C 2 H 5 0. Made by action of ethyl 
iodide on sodium methylate, thus : 

C 2 H 5 I + NaOCHs = Nal + GH5OCH3. 

Properties. Colorless, volatile, inflammable liquid; boils at 
ii°. Used as anaesthetic. 

Acetic Ether, Ethyl Acetate, (C 2 H 5 ) (C 2 H 3 2 ). Made by 
distilling a mixture of sodium acetate, ethyl alcohol and sul- 
phuric acid, shaking the distillate with calcium chloride and 
redistilling. The reaction is represented thus : 

GH 5 OH + NaC 2 H 3 2 + H 2 SO. = C 2 H 5 C 2 H 3 2 + NaHSO* + H 2 0. 

Properties. Clear, colorless, volatile liquid; aromatic odor, 
pungent taste; soluble in chloroform, alcohol, ether and 17 parts 
water. 

Ethyl Nitrite, Nitrous ether, C 2 H 5 N0 2 . Made by distil- 
ling a mixture of ethyl alcohol, sodium nitrite and sulphuric 
acid ; washing with cold water and sodium carbonate, to remove 



298 TEXT-BOOK OF CHEMISTRY 

alcohol and neutralize acid ; and mixing with dried potassium 
carbonate, to remove water. 

Properties. Mobile liquid, agreeable odor, sweet taste, boils 
at 86°. Used in making sweet spirit of nitre, by dissolving four 
parts in 96 parts alcohol. 

Glyceryl Trinitrate, Nitroglycerine, C 3 H 5 (N0 3 ) 3 . Made 
by the action of a mixture of nitric and sulphuric acids on 
glycerine in the cold. 

Properties. A clear, colorless, or slightly yellowish, oily 
liquid ; soluble in alcohol and ether, insoluble in water ; sweetish, 
burning taste ; poisonous ; solidifies at — 20 ; burns when 
heated in an open vessel, but explodes if the heat exceed 250 , 
or by concussion. Dynamite is nitroglycerine mixed with in- 
fusorial earth. Spirit of glonoin is a one per cent, alcoholic 
solution of nitroglycerine. 

Amyl Nitrite, QH^NCV Made like ethyl nitrite. 

Properties. A clear, pale-yellow liquid ; aromatic, apple-like 
odor ; burning taste ; specific gravity 0.872, boiling point at 96 . 

Nitrite of amyl is used in medicine to lessen arterial tension 
and stimulate the heart's action, it is administered by inhalation. 

The Natural Fats. 

The natural fats, or true fats, are compound ethers formed 
by the union of the radical of the triatomic alcohol glycerine, 
C 3 H 5 (OH) 3 , with fatty acids ; chiefly oleic, palmitic and stearic 
acids. The salts formed by this union are known as olein, 
C 3 H 5 .(C 18 H 33 2 ) 3 ; palmitin, C 3 H 5 .(C 16 H 31 2 ) 3 ; and stearin, 
C 3 H 5 . (C 18 H 35 2 ) 3 . Of these three compounds, olein is a liquid 
at the ordinary temperature, while palmitin and stearin are 
solids ; and the fat is liquid or solid, according to the propor- 
tionate quantities of these constituents. 

The fat oils are distinguished from the essential oils by the 
permanent stain which fats produce upon paper, and by their 
non-volatility. 



ETHERS AND ESTERS 299 

Occurrence in Nature and Properties of Fats. The fats 
are found in minute quantity in all" parts of plants, and in all 
parts of animal tissues except normal urine. They occur in 
abundance in the seeds of many plants, and under the skin and 
around the intestines of animals. 

When pure, they are colorless, odorless, and tasteless, though 
taste, color and odor are often imparted by foreign substances 
or products of decomposition. The decomposition of fats is 
known as rancidity; in which the fatty acid is liberated. All 
fats are lighter than water, and the solid ones fuse below the 
boiling point of water (ioo°) ; they cannot be distilled at the 
atmospheric pressure without decomposition. When fats are 
heated, some of the decomposition products formed have an 
exceedingly disagreeable odor, as is shown in the case of 
acrolein, an aldehyde formed from glycerine by dehydration. 

Some of the fats absorb oxygen of the air and generate 
sufficient heat to set fire spontaneously to cotton or wool satur- 
ated with them. These fats become thick and finally form solid 
shining masses. On account of these properties they are largely 
used in painting, and are called drying oils. Examples of dry- 
ing oils are croton oil, linseed oil, hemp oil, castor oil and cod- 
liver oil. Their drying properties are due to the presence of 
linoleic acid instead of oleic acid. The presence of albuminous 
impurities, which prevent the hardening of drying oils, may be 
removed by shaking with sulphuric acid. 

Non-drying oils of importance are almond oil, palm oil, 
cocoanut oil, olive oil and cotton-seed oil. 

Waxes, while they are not glycerides like ordinary solid and 
liquid fats, are compound ethers showing great resemblance to 
fats. The liquid waxes are esters of monatomic alcohols, and 
include dolphin oil and sperm oil. The solid waxes are esters 
of the higher monatomic alcohols, with higher fatty acids in 
the free state. They include beeswax, Chinese wax and sper- 
maceti. 



300 TEXT-BOOK OF CHEMISTRY 

Decomposition of Fats is brought about in various ways, 
depending upon the products it is desired to form : 

1. By the action of metallic oxides in the presence of water, 
whereby a salt of the metal with the organic acid is formed and 
glycerine is set free. This method is employed in making 
lead plaster, which consists in boiling olive oil with lead oxide 
(litharge) and water, until a homogeneous mass results. Lead 
plaster is chiefly oleate of lead, which is completely insoluble 
in water, but soluble in benzene and chloroform. This equa- 
tion represents its formation: 

2CsH 5 (C ls H330 2 ) 3 + 3 PbO + 3 H 2 = 2C 3 H 5 (OH) 3 + 3Pb(C 18 H330 2 ) 2 . 

Olein Lead oxide Water Glycerine Lead oleate 

2. By the action of steam or water, under pressure, resulting 
in the separation of glycerine and the fatty acid, thus : 

GH,(GbH«O0. + 3H 2 = C 3 H B (OH) 3 + 3H.C 18 H 35 2 . 

3. By action of alkaline hydroxides, resulting in formation of 
a salt of the alkali with the fatty acid, or soap, and liberation of 
glycerine. Soft soap is formed from potassium; hard soap, 
from sodium. The reaction is represented in the equation : 

C3H 5 (C 18 H 33 2 ) 3 + 3NaOH = 3NaC 18 H 33 2 + QH 5 (OH) 3 . 

Green soap, soft soap, is made from linseed oil by action of 
caustic potash. It is a yellowish-brown soft-solid, soluble in 
water and alcohol, used for medical and surgical purposes. 

Liniment of ammonia is made by mixing ammonia water and 
cotton-seed oil, with 5 per cent, of alcohol. It contains ammo- 
nia soap. 

Liniment of lime, carron oil, made by shaking up a mixture 
of equal parts of lime water and linseed oil or olive oil. It con- 
tains calcium soap. 



CARBOHYDRATES 301 

CARBOHYDRATES, OR SACCHARIDS. 

This group of organic bodies embraces a number, of impor- 
tant compounds widely distributed in the vegetable kingdom, 
and largely used as food in the support of animal life. 

As originally defined, these compounds were said to contain 
six atoms of carbon, or some multiple of six, in the molecule, 
and hydrogen and oxygen in the proportions to form water. 
While this statement is true in reference to most of these bodies, 
it cannot be taken as a definition ; for carbohydrates have been 
made whose molecules contain carbon in quantities which have 
no relation to six, and others are known in which hydrogen and 
oxygen are not combined in the proportions to form water. 
While the term carbohydrate is no longer restricted to the 
bodies which it formerly included, the name is still retained in 
its broadened sense. 

The carbohydrates are aldehydes and ketones of the hexa- 
tomic alcohols, in some cases, and in others, they are the anhy- 
drides of these aldehydes. The hexatomic alcohol C 6 H s (OH) 6 
is derived from the hydrocarbon hexane by replacement of six 
hydrogen atoms by 60H. By gentle oxidation of this alcohol 
hydrogen is removed, and it is converted into the corresponding 
aldehyde, C 6 H 12 6 , mannose, a sugar, having the formula of 
a number of the carbohydrates, all of which behave like 
aldehydes. 

A second group of the carbohydrates, having the formula 
C 12 H. 22 11} are probably anhydrides of the group C 6 H 12 O e . 
Thus : 2C 6 H 12 O e — H 2 = C 12 H 22 11( 

A third group of the carbohydrates, having the formula 
C 6 H 10 O 5 , are still more complex anhydrides of the first. Thus : 
(C 6 H 12 O 6 )-H 2 O=(C 6 H 10 O 5 )„„. ' 

These anhydrides, by processes of hydrolysis, may be made 
to take up water, and thus revert to the other forms. The 
aldehvdic nature of the carbohydrates is shown in the case of 



3 02 TEXT-BOOK OF CHEMISTRY 

glucose which, by further oxidation, is converted into an acid, 
and, by action of nascent hydrogen, is reconverted into the 
alcohol, mannitol; a behavior similar to that which we have 
seen in other aldehydes. 

The bodies studied in this group are sugars, starches, gums 
and a number of compounds obtained by artificial means. The 
termination, ose, is generally used in naming these bodies to 
indicate that they belong to the same natural group. 

Occurrence in Nature. Carbohydrates are found in great 
abundance in the vegetable kingdom as starch, sugar and cellu- 
lose. In the animal kingdom they are found also, as represented 
by milk-sugar and bees' honey. 

General Properties. Most of the carbohydrates, when 
pure, are white solid substances, usually soluble in water. Some 
of them have a more or less sweet taste. They are not volatile, 
and easily undergo decomposition by the action of heat. The 
carbohydrates are either fermentable, or can usually be con- 
verted into fermentable substances. They are neutral in re- 
action, and behave like aldehydes — being converted into acids 
by oxidation, and, in some cases, forming alcohols by action 
of nascent hydrogen. Many of them are active reducing agents, 
deoxydizing alkaline solutions of salts of copper, mercury and 
bismuth. 

Classification of Carbohydrates. They were formerly 
classified into three groups, according to composition, thus : 



Glucoses. 


Saccharoses. 


Amyloses. 


CeH^Oe. 


C12H22O11. 


CeHioOs. 


Grape-sugar. 


Cane-sugar. 


Starch. 


Fruit-sugar. 


Melitose. 


Dextrin. 


Mannitose. 


Maltose. 


Gums. 


Inosite. 


Milk-sugar. 


Cellulose. 
Glycogen. 



The above system of classification is not sufficiently compre- 
hensive to include all the carbohydrates at present known, so 
they have been rearranged in the three following groups: 



CARBOHYDRATES 



303 



Mono-saccharids are carbohydrates which, by digestion with 
dilute acids, do not yield any other forms of sugar. They are, 
therefore, the simplest of the sugars, and include the members 
of the class formerly referred to as glucoses. They contain 
from three to nine carbon atoms in the molecule, an equal num- 
ber of oxygen atoms, and twice as many atoms of hydrogen. 
These sugars are 'named according to the number of carbon 
atoms they contain, thus : 

Trioses, three carbon atoms; Tetroses, four carbon atoms; 
Pentoses, five carbon atoms ; Hexoses, six carbon atoms ; Hep- 
toses, seven carbon atoms ; Octoses, eight carbon atoms ; 
Nonoses, nine carbon atoms. 

The group of hexoses embraces the best-known members of 
this class ; the others are chiefly of scientific interest. 

The Di-saccharids are carbohydrates which split up into 
two different sugars, when boiled with dilute acid. These in- 
clude the sugars found in the group of saccharoses of the old 
classification : Pentabioses, C 10 H 18 O 9 ; Hexabioses, C-^H^On ; 
Hexatrioses, C 18 H 32 16 . 

The Poly-sac charids comprise carbohydrates of vegetable 
origin whose molecular formulae have not been determined; 
they split into more than two different sugars when boiled 
with dilute acid. Some are crystallizable as gentianose, of 
gentian root, and lactosan of soap bark. Others are non-crys- 
tallizable and represented by starches, dextrins and celluloses, 
corresponding to the amyloses of the old classification: 

1. Monosaccharids. 

Properties. Neutral, colorless, odorless, and sweet-tasting 
bodies, easily soluble in water, insoluble in ether, slightly soluble 
in alcohol. 

They are aldehydes and ketones and are easily oxidized and, 
therefore, reduce certain metallic salts, such as copper. 



304 TEXT-BOOK OF CHEMISTRY 

3 6 9 

The trioses, hexoses and nonoses readily undergo alcoholic 

6 7 8 

fermentation ; the pentoses, heptoses and octoses do not. Of 

the monosaccharids the hexoses are of practical interest. 

The Hexoses, or Glucoses, are divided into two groups : 
The aldehyde, or aldose group; and the ketone, or ketose 
group. 

The members of the aldehyde group of interest are : 

Dextrose, Glucose, or Grape-sugar, C 6 H 12 6 . Found 
widely distributed in the vegetable kingdom, in grapes, in most 
sweet fruits, in sprouting grains, and in honey ; generally occurs 
with an equal amount of levulose. Occurs in minute quantity in 
blood and, in large amount, in diabetic urine. 

Formed in plants by action of vegetable acids on starch. 
Artificial preparation by boiling starch, or cellulose, with dilute 
mineral acid, forming first dextrin and then dextrose, neutraliz- 
ing the acid with lime, and drawing off the clear liquid and 
evaporating. 

Properties. Generally seen as a syrup, or thick liquid, but 
may be obtained crystalline. Soluble in own weight of water, 
slightly soluble in alcohol, less sweet than cane sugar. It first 
loses water when heated and is converted into glucosan 
C 6 H 10 O 5 , and then forms caramel. Dextro-rotary ; a strong re- 
ducing agent ; combines with various oxides and other bodies 
to form glucosides. 

Mannose, C 6 H 12 O e , is obtained by careful oxidation of man- 
nite, C 6 H 8 (OH) 6 . It is a hard, friable powder; resembles 
grape sugar. 

Galactose, C 6 H 12 6 (Cerebrose). Formed with dextrose 
when milk-sugar, gums and mucilages are boiled with dilute 
H 2 S0 4 . Formed by decomposition of the glucoside, cerebrin, 
which is found in the brain. May be separated from dextrose 
by its solubility in absolute alcohol. Crystalline solid, reduces 
copper solution and ferments with yeast. 






CARBOHYDRATES 30 5 

Members of the Ketone group of hexoses are : 

Levulose, C 6 H 12 6 {Fructose), Fruit-sugar. Occurs mixed 
with glucose in sweet fruits and honey. Made by heating cane- 
sugar with dilute acids, which forms dextrose and levulose. 
Separated from former by mixing with slacked lime and water, 
when levulose forms an insoluble compound with calcium, which 
is separated and decomposed with C0 2 . 

Properties like glucose, but may be crystallized from alcohol ; 
sweeter, levo-rotary. Easily assimilated; does not increase 
sugar in urine of diabetics, and used for them as " diabetin." 

Inosite (muscle-sugar), C 6 H 12 6 . Occurs in muscles, 
lungs, liver, kidney, spleen, brain. In vegetable kingdom, in 
unripe beans. 

Properties. Only resemblance to sugars is sweet taste. 
Now thought to be a derivative of benzene, and not a sugar. 
Large, efflorescent, rhombic tables, or lumps of fine crystals ; 
soluble in water and dilute alcohol. 

2. Disaccharids, or Saccharoses. 

An important class. All capable of hydrolysis by dilute acids 
and certain ferments, yielding monosaccharids. This process is 
called inversion. Cane sugar does not reduce Fehling's solu- 
tion ; the other members do. 

Cane-sugar, Saccharose, Saccharum, Sucrose, Beet-sugar, 

^-'12 -22^-^11" 

Occurrence in Nature. In juices of many plants, in fruits, 
in juice of sugar cane (Saccharum ofhcinarum), sorghum 
(Sorgo saccharatum), beet root, maple and several species of 
palm. Found in plants containing no free acid. 

Prepared by expressing the juices of cane sugar, heating 
and adding milk of lime, to precipitate vegetable albuminous 
matter and phosphates. The clear liquid is then evaporated, 
filtered through bone charcoal, and concentrated in vacuum 

21 



306 TEXT-BOOK OF CHEMISTRY 

pans to crystallize. The residue of " mother liquor " is used as 
syrup. 

Properties. When allowed to crystallize slowly, it forms 
large, prismatic, transparent crystals, called " rock candy." It 
also forms hard, white, granular crystals. Sugar is soluble in 
.5 parts cold water, and in all proportions of hot water, and in 
175 parts of alcohol. It fuses at 160 , and forms an amorphous 
transparent mass known as "barley sugar " ; at higher tempera- 
tures it turns brown, forming caramel, and finally oxidizes by 
further heating. 

Cane-sugar is a strong reducing agent ; this property can be 
shown by mixing it with chlorate of potash and sulphuric acid, 
when violent deflagration takes place. An acid solution of 
potassium permanganate is decolorized by a solution of cane- 
sugar for the same reason. 

Cane-sugar does not reduce alkaline copper solution; it is 
not directly fermentable, but can be converted into fermentable 
forms ; it produces compounds with many other bodies, and 
these compounds are called Sucrates. 

Lactose, Milk-sugar, Saccharum Lactis, C 12 H 22 11 .H 2 0. 
This sugar is found in the milk of mammals. It is made by 
evaporating the whey of cow's milk. Cow's milk contains from 
four to five per cent, of milk-sugar ; human milk contains from 
six to seven per cent. 

Properties. Milk-sugar occurs in hard, white, prismatic 
crystals or masses ; it is soluble in six parts of cold water, or 
one part of boiling water. 

This sugar is not so sweet as cane sugar ; it does not ferment 
readily with yeast, but ferments to lactic or butyric acid by 
the action of these ferments ; it reduces alkaline copper solution. 

Maltose, Malt-sugar, C 12 H 22 11 . In the germination of 
grain, malt-diastase is formed, and this ferment, acting upon 
starch present in the grain, produces malt-sugar. Extracts of 



CARBOHYDRATES ^°7 

malt are used in medicine for the purpose of aiding the diges- 
tion of starchy foods ; the diastase of these extracts converting 
the starch into malt-sugar, a soluble form of carbohydrate. 

Malt-sugar is also formed by the action of saliva or of dilute 
sulphuric acid on starch ; the continued action of sulphuric acid 
on starch results in the formation of dextrose. 

Maltose is soluble in water or alcohol ; it crystallizes in fine 
needles ; it ferments with yeast to form alcohol ; it reduces 
alkaline copper solution. 

Melitose is a sugar obtained from Australian manna. 

3. The Polysaccharids. 

To this group belong a great number of carbohydrates of 
high molecular weight, generally insoluble, not diffusible, and 
capable of splitting into more than two sugars by the action 
of dilute acids and ferments. When boiled with acids they gen- 
erally change into dextrin, di-saccharids, and finally, mono- 
saccharids. The exact molecular weight is not known, but by 
reference to Raoult's method the probable molecular weight of 
dextrine is (C 6 H 10 O 5 ) 12 , and of soluble starch, (C 6 H 10 O 5 ) 30 . 

The subdivisions of this group embrace the starch group, 
the cellulose group, and the gum group. 

(a) The Starch Group. 

Starch, Amylum, (CeH^Og).. Starch is found in nearly 
all plants, in the seeds, roots and stems ; it occurs most abund- 
antly in the cereals, rice, potatoes, and the seeds of plants. 
Microscopic starch granules are imbedded in the cells of the 
plant, in much the same way as fat granules occur in the animal 
body. 

Starch granules are somewhat oval in shape, having an eccen- 
tric nucleus around which are placed concentric layers of sub- 
stance, resembling the appearance of an oyster-shell. In potato- 
starch the granules are large and oval, in corn-starch the gran- 



308 TEXT-BOOK OF CHEMISTRY 

ules are less oval and much smaller. The source from which 
starch is obtained may be determined by means of the micro- 
scope, on account of differences in appearance* of the granules. 

The preparation of starch is a mechanical process, which con- 
sists in first comminuting or grinding the vegetable substance, 
and then washing with water. In this way the starch granules 
are removed, and the water may be separated by decantation. 

Properties. White, amorphous, odorless, tasteless, friable 
masses ; insoluble in cold water, alcohol or ether. When starch 
is boiled with water, the granules swell, and finally burst, form- 
ing a thick mucilaginous liquid, known as starch paste ; by long 
boiling it is converted into soluble dextrine. The conversion 
into dextrine is also produced by dry heat at 175°, or by boil- 
ing with dilute sulphuric acid. 

The characteristic test for starch is iodine. This test is ap- 
plied by mixing an aqueous solution of iodine with cold muci- 
lage of starch, when a deep blue color is produced. 

Glycogen, (C 6 H 10 O 5 ) w . Glycogen occurs in the liver of 
animals, in the yolk of egg, the embryo and in some mollusks. 

Glycogen resembles dextrine ; it dissolves in water, but is 
insoluble in alcohol or ether ; it is dextro-rotary. Glycogen of 
the liver is changed to maltose and dextrose by a liver ferment 
or the liver cells. Iodine gives a reddish-brown color with 
glycogen which disappears on heating and returns when cooled. 

Glycogen may be prepared for experiment as follows : 

Preparation. Use a liver taken from an animal just killed, 
or oysters just removed from the shell. Cut one half rapidly 
into small pieces and place it into four times its weight of boil- 
ing water which has been slightly acidified with acetic acid. 
Lay the other half aside, keeping it moist for twenty-four hours, 
for subsequent examination. See page 313. 

After boiling the first portion for a few minutes, remove the 
pieces, grind in a mortar with clean sand, return to the water, 



CARBOHYDRATES 3O9 

and continue boiling for several minutes ; filter while hot. The 
liquid thus obtained has an opalescent appearance, and contains 
glycogen in solution. 

The solution of glycogen may be purified as follows : Add, 
alternately, a few drops of hydrochloric acid and potassium 
mercuric chloride, as long as a precipitate of proteids forms. 
This may be determined more accurately by testing a small 
portion of the liquid separately from time to time. When the 
precipitation is complete, filter, and add to the filtrate, double 
its volume of alcohol ; the glycogen will precipitate as a white 
powder. Filter, and wash the precipitate with a mixture of 
one part water and two parts alcohol. Dissolve the residue in 
water. 

(b) The Cellulose Group. 

Cellulose, Lignine, Plant Fibre, (C 6 H 10 O 5 ) 3 . Occurs in 
nature as plant skeleton ; also as cotton, hemp and flax. Ab- 
sorbent cotton is pure cellulose. 

Properties. White, translucent, insoluble : soluble in ammo 
niacal solution of basic cupric carbonate. 

Cellulose does not give a blue color with iodine. When mixed 
with sulphuric acid it swells, dissolves, and is precipitated from 
solution by adding to water ; this precipitate is called amyloid. 
Amyloid, as its name implies, is closely related to starch, and 
gives a blue color with iodine. 

Cellulose is converted into dextrine and dextrose by boiling 
with diluted sulphuric acid. 

Parchment paper is made from cellulose by dipping paper 
into a solution made by mixing two volumes of sulphuric acid 
and one volume of water. 

Trinitro cellulose, C 6 H 7 2 (N0 3 )3, is explosive gun-cotton. 
Made by steeping cotton in a mixture of one part strong nitric, 
and three parts strong sulphuric acid, for a few minutes ; re- 



310 TEXT-BOOK OF CHEMISTRY 

moving, squeezing dry, and placing in fresh acid forty-eight 
hours; removing, pressing dry, washing with water, and then 
weak sodium carbonate solution. The cotton retains its ap- 
pearance, but is very explosive. 

Tetranitro cellulose, or pyroxylin, is used for making collo- 
dion by dissolving in a mixture of ether and alcohol. Gun- 
cotton is used in making smokeless powder. Formation of the 
different compounds dependent upon length of time cotton is 
acted on by the acids. 

(c) The Gum Group. 

These are amorphous, of vegetable origin, soluble in water 
or swelling in it like tragacanth, insoluble in alcohol, converted 
into glucose by boiling with dilute sulphuric acid. 

Dextrine or British Gum (C 6 H 10 O 5 ) w . Preparation. By 
action of dilute acid on starch, or dry heat to 175 , or action of 
diastase on starch. 

Properties. Colorless, or yellowish, amorphous powder ; re- 
sembles gum arabic ; soluble ; reduces copper solution ; colored 
wine-red by iodine. 

Acacia, Gum Arabic. Exudation from Acacice Senegal. 
In composition it is said to be the calcium salt of arabic acid. 

Properties. Soluble in two parts water ; solution has acid 
reaction with litmus, and precipitates with lead acetate or ferric 
chloride. Gums from cherry, peach, flaxseed, &c, are members 
of this group. 

Practical Note. — In the treatment of certain diseases, such as diabetes 
mellitus, it becomes necessary to exclude carbohydrate food from the 
diet, as far as possible. Articles of food containing a minimum quan- 
tity of carbohydrate are as follows : Meats of all kinds, fresh or salted ; 
soups made from meat without flour; game, poultry, oysters, fish, lob- 
sters, crabs, eggs, butter, new cheese, oils and fats. All vegetable sub- 
stances contain carbohydrate in the form of cellulose, or plant fibre, but 
in a case of diabetes, the green vegetables are allowed, as they do not 



CARBOHYDRATES ' 3 I I 

contain starch or sugar to any great extent. The green vegetables 
referred to are cabbage, Brussels sprouts, spinach, endive, the green 
leaves of lettuce, cauliflower, broccoli, string beans, tomato, water 
cresses, celery tops, asparagus tops, turnip tops, young onions, cucum- 
ber, pickles and olives. Of fruits, and other articles permitted in a 
carbohydrate-free diet, are apples, lemons, strawberries, almonds, wal- 
nuts, butter-nuts, pecans, filberts, Brazil nuts, but not chestnuts. To 
these may be added unsweetened jellies, cream, milk, buttermilk, un- 
sweetened tea or coffee; claret, Burgundy, still Moselle, and sherry 
wines ; brandy, whiskey, gin and carbonated waters. 

Tests for Carbohydrates. 

I. MONOSACCHARIDS. 

Glucose. Employ a three per cent, aqueous solution. 

1. Trommers Test. To about 5 cc. of solution in a test- 
tube add an equal volume of strong solution of caustic soda or 
caustic potash solution, and then a dilute solution of cupric 
sulphate, drop by drop, as long as the precipitate formed con- 
tinues to redissolve, forming a clear blue liquid. Heat the mix- 
ture, and note the reddish-yellow precipitate of cuprous oxide. 
Apply the same test to normal urine and to diabetic urine. 

2. Fehling's Test. Fehling's solution is made as follows : 
Dissolve 34.64 gm. of pure crystallized cupric sulphate in water 
to make 500 cc. Dissolve 173 gm. pure crystallized sodium 
potassium tartrate, and 60 gm. sodium hydroxide, each in 200 
cc. of water and make up to 500 cc. with distilled water. When 
the solution is to be used, mix equal quantities of the copper 
sulphate and sodium tartrate solutions. Ten cc. of the mixed 
solutions will be reduced by .05 gm. of glucose. 

Boil a few cc. of the Fehling's solution in a test-tube (it 
should remain clear) and then add a few drops of the glucose 
solution and allow to stand a few minutes. Notice the precipi- 
tate of reddish-yellow cuprous oxide. Apply the above test to 
normal and diabetic urine. 

Note. — A flocculent, yellowish precipitate is sometimes produced, 
when Fehling's solution is heated with urine, by an excess of urates or 
earthy phosphates, which must not be mistaken for glucose. 



3 I 2 TEXT-BOOK OF CHEMISTRY 

3. Boettger's Test. To some of the glucose solution add an 
equal volume of strong sodium carbonate solution (1 in 3), 
and then a little bismuth subnitrate : shake and boil. The 
subnitrate assumes a grayish or black color, depending on the 
amount of glucose present. Albumen and substances contain- 
ing sulphur interfere with this test. 

4. Fermentation Test. Fill a test-tube with the glucose solu- 
tion, add some yeast and invert over a dish containing the same 
solution. Allow the test-tube to stand for twenty-four hours, 
and test the evolved gas (C0 2 ) with lime-water. 

2. Dl-SACCHARIDS. 

(a) Cane-sugar. Use a 2 per cent, aqueous solution. 

1. Apply tests 2 and 3, and note the negative results. 

2. To some of the solution in a test-tube add a few drops of 
dilute sulphuric acid ; boil for several minutes, allow to cool, 
neutralize with caustic soda and re-apply tests 2 and 3. Ob- 
serve that the sugar has undergone inversion by action of the 
acid, being converted into dextrose and levulose. 

(b) Maltose. Use a 2 per cent, aqueous solution. 
Apply tests 2 and 4, comparing with glucose. 

3. POLY-SACCHARIDS. 

(a) Starch. 1. Examine under the microscope and note 
the characteristic granules. Examine the granules of potato, 
corn, wheat and rice starch, noting the differences in appear- 
ance. 

2. Solubility. Test by adding water to powdered starch, 
filter, and test the filtrate by adding a drop of iodine solution. 
Notice that no reaction is obtained. 

3. Starch Paste. Take a small quantity of starch and rub 
with a little water, then pour the mixture into about 25 cc. of 
boiling water, allow the liquid to cool and notice that it ac- 
quires a mucilaginous appearance and consistency. Add 
iodine solution and note blue color. 



CARBOHYDRATES ' 313 

4. Add a few drops of solution of tannic acid to the starch 
solution ; a yellowish precipitate is formed, soluble upon appli- 
cation of heat. 

5. Test the starch solution with Fehling's solution and note 
the negative result. 

6. Boil 25 cc. of the starch solution with a few drops of 
dilute sulphuric acid for ten minutes and note the change in 
appearance. Neutralize a portion of this solution with caustic 
soda and test with Fehling's solution. Note reaction for 
glucose. 

7. To about fifteen cc. of the starch solution add a few cc. 
of saliva and heat in the water-bath at about 40 ° C. for fifteen 
minutes. Test the resulting solution with Fehling's solution 
and note the reduction, indicating maltose. 

(b) Dextrine. 1. Employ a 2 per cent, aqueous solution of 
pure dextrine and apply the tests given under starch, noting 
the results. 

2. Add a few drops of the dextrine solution to some alcohol 
in a test-tube and note the precipitate which is redissolved by 
adding water. 

3. Add basic lead acetate solution to the solution of dextrine 
and note the result. 

(c) Glycogen. The glycogen solution obtained as directed 
on page 308, may be tested as follows : 

1 . Add a drop of iodine solution to a portion of the glycogen 
solution in a test-tube, and note the dark-red color. This color 
disappears on heating and returns when the liquid cools. Com- 
pare with dextrine. 

2. Test with Fehling's solution and note the negative result. 

3. Boil with a few drops of dilute sulphuric acid, neutralize 
with sodium hydroxide, and apply Fehling's solution; note 
reaction for glucose. 

4. Add basic lead acetate solution and compare with dex- 
trine. 



314 TEXT-BOOK OF CHEMISTRY 

5. Add saliva to some of the glycogen solution and heat for 
fifteen minutes on the water-bath at 40 C. Divide into two 
portions : test one half with iodine solution for glycogen, and 
the other half with Fehling's solution for sugar. 

Make an extract of the half of the liver or oysters that has 
been reserved. See page 308. Test for glycogen with iodine 
solution, and for reducing sugar with Fehling's solution. 

GLUCOSIDES. 

Glucosides are compounds which decompose by the action 
of dilute acids, forming glucose or a related carbohydrate. The 
decomposition of a glucoside appears to be a process of hydra- 
tion, and it is effected not only by the action of dilute acids but 
by boiling with weak alkalies, and by the action of ferments. 
The glucosides are usually obtained from the vegetable king- 
dom. 

The chemical behavior of glucosides indicates that their 
structure corresponds to the molecule of a compound ether, in 
which glucose takes the part of the basic radical. 

Glucosides are prepared from the plant in which they occur 
by extracting with water or alcohol, decolorizing with animal 
charcoal, and crystallizing by evaporation. They can be made 
artificially by dissolving glucose in different alcohols, and pass- 
ing gaseous hydrochloric acid through the solution. 

The glucosides are usually neutral, soluble in water and 
capable of being crystallized. Some of them, such as solanin, 
contain nitrogen and resemble the alkaloids ; others, such as 
myronic acid, have a slightly acid character. Many of them 
are optically active, but the direction of their rotation shows 
no relation to the sugar formed by their decomposition. Some 
of the glucosides represent the active principles of plants and 
are employed in medicine, like alkaloids. The termination, in, 
is generally employed in naming the members of this class. 



GLUCOSIDES * 3 I 5 

The names and source of some of the more important gluco- 
sides are as follows : 

Adonin, obtained from Adonis vernalis, and sometimes used 
as a cardiac tonic. 

Amygdalin, C^H^NO-^, is found in the bitter almond and 
cherry-laurel. Amygdalin decomposes by action of the fer- 
ment, emulsine, in presence of water, forming glucose, benzoic 
aldehyde, and hydrocyanic acid. It is a white, crystalline 
powder. 

Arbutin is a bitter substance found in Uva ursi. 

Cathartic acid is found in senna. 

Colocynthin is a purgative principle found in colooynth-fruit. 

Digitalin is obtained from Digitalis purpurea, and it con- 
sists of a mixture of glucosides, viz. : Digitonin, C 31 H 52 17 , a 
yellowish, amorphous body; soluble in diluted alcohol. Digi- 
talin, C 5 H 8 2 , a crystalline, bitter solid ; soluble in alcohol ; in- 
soluble in water. Digitalein, a white, amorphous, bitter solid ; 
soluble in water or alcohol. Digitoxin, C 21 H 82 7 , a colorless, 
crystalline solid ; slightly soluble in alcohol ; insoluble in water. 
Digitoxin is not a glucoside. 

Myronic acid, C 10 H 19 NS 2 O 10 , found as potassium; salt in 
black mustard-seed oil. This salt is called sinagrin; it is de- 
composed by action of the ferment, myrosin, into dextrose, 
allyl mustard oil and potassium bisulphate. 

Allyl mustard oil, C3H5NCS, is the sulphocyanide of the radical, C 3 H 5j 
from propylene, C3H6, isomeric with glyceryl. Glyceryl may be con- 
verted into allyl alcohol, C3H5OH, and artificial mustard oil can be 
made from this. Mustard oil is a pale-yellow liquid, acrid odor and 
burning taste. Allyl sulphide, (CsHs^S, is found in garlic. 

Phloridzin is obtained from bark of the root of apple, cherry 
and pear ; its introduction into the circulation causes glycosuria. 

Salicin, C 13 H 18 7 , is found in the willow. It decomposes into 
glucose and salicylic alcohol, (C 6 H 4 OHCH 2 OH). Salicylic 



3l6 TEXT-BOOK OF CHEMISTRY 

alcohol may be oxidized into salicylic acid. Salicin occurs 
in white, silky, needle-shaped crystals ; soluble in water ; bitter 
taste. 

Strophanthine is found in the seeds of strophanthus. It is 
used as a heart tonic. 

Solanin, a poisonous body found in potato-sprouts and in 
other solanaceous plants. 

NITROGENOUS BODIES OF SIMPLE STRUCTURE. 

The nitrogen of organic bodies is contributed from three 
sources, viz., ammonia, cyanogen and nitric acid, or derivatives 
of these compounds. In many of the complex nitrogenous 
bodies of the aromatic series, and in the nitrogenous bodies of 
the proteids, nitrogen is contained in the ammonia forms. 

In the present chapter, only those nitrogenous bodies having 
a simple structure will be considered. 

The ammonia forms of nitrogen embrace the amines, amides 
and amido-acids and their derivatives. These are found in the 
various organic bases, generally known as alkaloids, and occur- 
ring as the product of animal or plant life. 

The cyanogen forms of nitrogen contain the compound 
radical cyanogen, CN, and constitute the group of bodies 
known as cyanogen and cyanides. 

The nitric acid forms comprise the organic nitrates, nitrites, 
and nitro-compounds. Nitro-compounds contain the radical 
N0 2 ; they differ from nitrites in the fact that this radical re- 
places hydrogen in forming nitro-compounds, while the N0 2 
group, in nitrites, is united to a basic radical, producing a com- 
pound ether. 

The nitric acid derivatives are not found in nature, but are 
made by artificial means, and they often constitute highly ex- 
plosive substances, such as nitro-glycerine, trinitro-cellulose, &c. 



NITROGENOUS BODIES OF SIMPLE STRUCTURE 3 1/ 

AMINES AND AMIDES. 

Amines are bodies formed by replacement of hydrogen in 
ammonia by alcohol radicals, thus : 

NH 2 (CH 3 ) NH 2 (C 2 H 5 ). 

Methyl amine Ethyl amine 

Primary amines are formed when one hydrogen atom is 
replaced by the radical ; secondary and tertiary amines are 
formed when two and three hydrogen atoms are so replaced. 

Ammonium bases are formed when all the hydrogen of the 
ammonium radical has been replaced by an alcohol radical, 

thus: 

N(CH 3 )40H, Tetra-methyl ammonium hydroxide. 

Amines are further subdivided into mon-amines, di-amines, 
tri-amines, &c, according as one, two, three or more molecules 
of ammonia are represented, thus : 

(NH 2 ) 2 C 2 H4, Ethylene diamine. 

The properties of amines are much like those of ammonia ; 
they are usually soluble, have an ammoniacal disagreeable odor, 
and are strongly basic ; they combine with acids with retention 
of hydrogen ; their chlorides form double compounds and pre- 
cipitates with perchloride of platinum. The amines formed 
from methane are gaseous, those formed from ethane are 
liquids. 

The resemblance of amines to ammonia is well shown in the 
following equation, which represents the reaction taking place 
between trimethylamine and hydrochloric acid, forming tri- 
methyl-amine hydrochloride, thus : 

N(CH 3 )3 + HC1 = N(CH 3 )3HC1. 

Notice that this base unites with the acid with retention of 
the hydrogen, to form a salt. 

Amides are derived from ammonia by replacement of its 
hydrogen atoms by acid radicals, thus : 

NH2(C 2 H 3 0), Acetamide. 



3 l8 TEXT-BOOK OF CHEMISTRY 

The naming of amides follows the same rules that apply to 
amines. 

In properties, the amides resemble ammonia like amines, but 
they are less basic than the latter, on account of the presence 
of the acid radical. 

Formamide, NH 2 CHO. Made by heating alcoholic solu- 
tion of ammonia with ethyl formate. Also made by dry dis- 
tillation of ammonium formate, thus : 

NH 4 HC0 2 = NH 2 HCO + H 2 0. 

Ammonium formate Formamide Water 

Properties. A colorless liquid, soluble in water or alcohol. 

Formamide combines with chloral to produce chloral-forma- 
mide, or chloralamide, having the formula, NH 2 CH0.C 2 HC1 3 0. 

Chloralamide is a colorless, slightly bitter, crystalline solid ; 
soluble in twenty parts of water. Hot water decomposes this 
compound into chloral hydrate and ammonium formate ; it is 
also decomposed by alkalies, but not by acids. Used as an 
hypnotic in ten to> forty grain doses. 

Amido-acids. The radical NH 2 is known as amidogen. 
When amidogen replaces the hydrogen of an acid radical, the 
resulting compound is an amido-acid, thus : 

H.C 2 H 2 (NH 2 )02, Amido-acetic acid. 

These compounds show both acid and basic properties, and 
many of them are formed during life in animal tissues. 

Amido-formic Acid, Carbamic acid, H.NH 2 C0 2 . This acid 
is found in commercial ammonium carbonate, as ammonium 
amido-formate, having the formula, NH 4 NH 2 C0 2 . The 
ammonium salt is produced by the action of carbon dioxide on 
ammonia, as shown in the following equation : 

C0 2 + 2NH3 = NH 4 NH 2 C0 2 . 

Amido-acetic Acid, Glycocol, C 2 H 3 (NH 2 )0 2 , can be made 



t 



NITROGENOUS BODIES OF SIMPLE STRUCTURE 319 

by boiling glue with alkalies or acids, or by heating mono- 
chlor-acetic acid with ammonia, thus : 

C 2 H 3 C10 2 + 2NH3 = C 2 H 3 (NH 2 ) 2 + NH 4 C1. 

Properties. Large, colorless, transparent crystals, of sweet 
taste.' 

This acid occurs in the body in hippuric and glycocolic acids, 
and in bile as sodium glycocholate. 

Amines and amides are found in nature as the products of 
animal life in certain organic bases, constituting the nitrog- 
enous end products of metabolism, such as urea, uric acid, 
creatin, &c. They are found as the products of vegetable life 
in alkaloids, and as products of putrefaction in ptomaines. 

Amines are formed: 

1. By destructive distillation, as aniline and pyridine. 

2. By the action of ammonia on the chloride or iodide of 
alcohol radicals, thus : 

C 2 H 5 C1 + NH 3 = NH 2 (C 2 H B ) + HC1. 

3. By action of nascent hydrogen on cyanides of alcohol 

radicals, thus: 

CH3CN + 2H 2 = C 2 H 5 NH 2 . 

4. By action of nascent hydrogen on some nitro-compounds, 

thus: 

C 6 H 5 N0 2 + 3H 2 = C 6 H 5 NH 2 + 2 H 2 0. 

Formation of Amides by action of ammonia on chloride of 
acid radical, thus : 

C2H3OCI + 2NH3 = C 2 H 3 ONH 2 + NH^Cl. 

Further study of these bodies will be deferred, when they 
will be again taken up as alkaloids. Alkaloids containing car- 
bon, hydrogen and nitrogen, are amines. Those containing 
carbon, hydrogen, nitrogen and oxygen, are amides. 



320 TEXT-BOOK OF CHEMISTRY 



CYANOGEN, (CN), Cy. 



N^C — C^N. — C = N. — N = C. 

Cyanogen molecule Nitrils, or cyanides Isocyanides, or carbylamines 

Cyanogen is the first compound radical whose distinct ex- 
istence was proved; it was discovered in 1811 by Gay-Lussac. 
The name, cyanogen, means " generator of blue," referring to 
the deep-blue compounds formed by this radical. 

Occurrence in Nature. Cyanogen is not found free in 
nature to any great extent; it is said to occur in the gases 
issuing from volcanoes and iron furnaces. In combination, 
cyanogen is found in certain plants, such as the wild cherry, 
bitter almonds and peach kernels, which, in common with most 
of the members of the same family, contain the glucoside, 
amygdalin. Amygdalin, by action of the ferment emulsine in 
the presence of moisture, undergoes decomposition, forming 
hydrocyanic acid, glucose and other bodies. Cyanogen is said 
to occur as the sulphocyanate of potassium in the saliva in 
minute amount. 

The chemical character of cyanogen is much like that of the 
halogens, and it was formerly classed as a member of this 
group ; it forms salts resembling the salts of these elements, and 
is precipitated from solution by silver nitrate in the form of 
white cyanide of silver, which has much the appearance of sil- 
ver chloride. The radical, when set free, forms a double mole- 
cule called di-cyanogen, (CN) 2 , whose structure is represented 
above in the graphic formula. 

Preparation. Though carbon and nitrogen cannot be made 
to combine directly, yet organic bodies containing carbon and 
nitrogen, when heated with caustic potash, yield potassium cya- 
nide. When iron is present the ferrocyanide of potassium is 
formed. From these compounds the other cyanogen compounds 
are made. 

Cyanogen (CN) 2 is prepared by heating mercuric or silver 
cyanide, thus: 



NITROGENOUS BODIES OF SIMPLE STRUCTURE 32 1 

Hg(CN) 2 + heat = Hg+(CN) 2 . 

Properties. A colorless gas, of pungent odor ; soluble in 
water and alcohol, easily liquefied at — 20.7 , and — 34 
freezes to snow-white solid. Burns with purple-red flame. 

Hydrocyanic Acid, HCN, Prussic acid. Discovered by 
Scheele in 1782. Found in water distilled from leaves and 
seeds of bitter almond, cherry and peach. Formed during de- 
structive distillation of coal. Can be made in many ways : 

1 . By action of ammonia on chloroform : 

CHCls + NH 3 = HCN + 3HCI. 

2. By heating ammonium formate : 

NH 4 HC0 2 = HCN + 2H 2 0. 

3. By action of dilute acids on metallic cyanides : 

AgCN + HC1 = HCN + AgCl. 

4. By heating potassium ferrocyanide with dilute sulphuric 
acid: 

2K 4 Fe(CN) 6 + 6H 2 SO* = K 2 Fe 2 (CN) 6 + 6KHSO4 + 6HCN. 
Properties. Pure hydrocyanic acid is a clear, colorless, 
mobile, volatile, inflammable liquid. The acid is miscible with 
water, alcohol or ether in all proportions ; its specific gravity 
is .697, boiling point 26 , and it solidifies to a white feathery 
mass at — 15 . It has the peculiar penetrating odor of bitter 
almonds. 

Pure hydrocyanic acid is one of the most rapid and violent poisons 
known. When the vapor is inhaled, instant death ensues; small quan- 
tities produce headache, giddiness, nausea, dyspnoea and palpitation and 
depression of the heart. The minimum fatal dose is said to be .9 of a 
grain of the anhydrous acid, though much larger quantities have been 
recovered from. 

The antidote is a mixture of a ferrous and a ferric salt with sodium 
carbonate, to form non-poisonous ferrocyanide of iron. Stimulants and 
artificial respiration must be resorted to — ammonia by inhalation and 
internally, and alcoholic stimulants— for the poison acts so rapidly there 
is no time to prepare the antidote. 
22 



322 TEXT-BOOK OF CHEMISTRY 

Used in medicine as dilute acid, of 2 per cent, strength. 

The dilute hydrocyanic acid can be made extemporaneously 
by action of six parts silver cyanide on five parts hydrochloric 
acid and fifty-five parts water, by weight, and decanting the 
clear liquid. It is a clear, colorless, acid liquid, having odor 
of peach kernels. 

Potassium Cyanide, KCN. Prepared by action of hydro- 
cyanic acid on alcoholic solution of caustic potash. Commer- 
cially made by heating a mixture of potassium ferrocyanide and 
potassium carbonate, and contains the cyanate : 

K 4 Fe(CN) 6 + K 2 C0 3 = 5KCN + KCNO + Fe + C0 2 . 

The resulting mass is washed with water, and the salt 
crystallized from this solution. 

Properties. A white, deliquescent, soluble salt, giving odor 
of hydrocyanic acid when moist. A solution of the salt under- 
goes decomposition on standing, and when heated is decom- 
posed to ammonium and potassium carbonates. Forms double 
salts with heavy metals. It acts as a violent poison, like the 
acid. 

Silver Cyanide, AgCN, precipitates as a white, insoluble 

powder when solutions of potassium cyanide and silver nitrate 

are mixed : 

KCN + AgN0 3 = KNO3 + AgCN. 

It shows much resemblance to silver chloride, is slowly solu- 
ble in ammonia water, and gives cyanogen gas when heated. 

Mercuric Cyanide, Hg(CN) 2 , is obtained by dissolving mer- 
curic oxide in hydrocyanic acid. It is a white, crystalline salt ; 
soluble in water and alcohol. Gives cyanogen when heated. 

Tests for Cyanides. 

1. Silver nitrate gives a white precipitate of silver cyanide, 
insoluble in dilute nitric acid, soluble in ammonia water. 

2. With ferrous and ferric salts, caustic potash and hydro- 



NITROGENOUS BODIES OF SIMPLE STRUCTURE ' 323 

chloric acid, gives a blue precipitate of Prussian blue, Fe^Fe- 
(CN) 6 . 

3. A dilute solution of picric acid, heated with hydrocyanic 
acid, gives a red color on cooling. 

Cyanogen enters into combination with iron to form acid 
radicals, in which the usual chemical reactions of the metal are 
not obtainable, and the poisonous properties of cyanogen are 
absent. These acids are hydro ferrocyanic acid, H 4 Fe(CN) 6 , 
in which iron is in the ferrous state ; and hydroferricyanic acid, 
H 3 Fe(CN) 6 , in which iron is in the ferric state. These acids 
are known in the form of their salts. 

Potassium Ferrocyanide, Yellow Prussiate of Potash, 
K 4 Fe(CN) 6 . 3 H 2 0. 

Preparation. By heating together refuse animal matter, 
potassium carbonate and iron scraps. 

6KCN + Fe + 2H 2 = K4Fe(CN) 6 + 2KOH + H 2 . 
The resulting mass is washed with water and the salt crys- 
tallized from this solution. 

Properties. Large, soft, translucent, pale-yellow, odorless, 
non-poisonous, neutral crystals ; soluble in water ; insoluble in 
alcohol. 

Tests for F err o cyanides. 

1. Blue precipitate with ferric salts — Prussian blue, Fe 4 3Fe- 
(CN), 

2. Burn when heated on platinum foil, leaving ferric oxide. 

3. With ferrous salts, a light blue precipitate, rapidly turn- 
ing darker. 

4. With cupric salts, a brownish red precipitate. 
Potassium Ferricyanide, Red Prussiate of Potash, K 3 Fe- 

(CN).. 

Preparation. By passing a stream of chlorine through solu- 
tion of potassium ferrocyanide : 

K 4 Fe(CN) 6 + CI = KC1 + K3Fe(CN)«. 



3^4 TEXT-BOOK OF CHEMISTRY 

In this reaction, an atom of potassium is removed from the 
ferrocyanide, and the iron passes from, the ferrous to the ferric 
state. 

Properties. Red, prismatic crystals, soluble in water. The 
solution, upon standing in light, gradually forms the yellow 
prussiate of potassium ; a similar change is caused by alkalies. 

Cyanic and Sulphocyanic Acids, HCNO and HCNS, form 
cyanates and sulphocyanates. These salts are formed by the 
direct action of oxygen, or sulphur, on the alkali cyanides, 
when an atom of one or the other, as the case may be, enters 
the molecule. The acids are colorless liquids. Potassium 
sulphocyanate is used as a reagent for ferric salts, with which 
it gives a deep-red color, discharged by mercuric chloride. It 
is obtained by fusing ferrocyanide of potassium with sulphur 
and potash. It occurs in colorless, deliquescent, soluble crystals. 

Iso-sulphocyanates. Constitution, as compared with sulpho- 
cyanates : 

— S— C=N — N=C=S 

Sulphocyanate Iso-sulphocyanate 

Ally I Iso-sulphocyanate, C 3 H 5 NCS, is found as mustard seed 
oil. A clear liquid, of irritating odor, blisters skin. 

Among organic cyanides two isomeric forms are known to 
exist, and these are denominated cyanides or nitrils, and 
isocyanides, or carbylamines. These two forms of cyanogen 
are represented graphically as follows : 

R_C = N and R — N = C. 

Nitrils or cyanides *3±?n~ 

3 carbylamines 

In the cyanides, nitrogen is trivalent; in the isocyanides, it 
is quinquivalent. 

These compounds appear to be esters, but are not saponifiable 
by action of caustic alkalies. 

Cyanides, or Nitrils may be made by heating together 
iodides of hydrocarbon radicals and potassium cyanide : 

CH 3 I + KCN = KI + CH 3 CN. 



NITROGENOUS BODIES OF SIMPLE STRUCTURE 325 

Properties. Volatile liquids, or solids. When heated with 
water and mineral acids, or alkalies, yield organic acids. 

Fulminic acid, H2N2C2O2. Seen in fulminate of mercury. Made by 
adding alcohol to a solution of mercury in nitric acid. Use in percus- 
sion caps. 

Isocyanides, or Carbylamines. Formed by heating silver 
cyanide with iodides of hydrocarbon radicals. 

CH3I + AgCN = CHsCN + Agl. 

Characterized by a very disgusting odor. 

Nitro Compounds contain the radical N0 2 . Isomeric with 
the nitrous acid esters, but differ from them in not being saponi- 
fiable by alkalies. Structure: 

— O — NO — N0 2 . 

Nitrite Nitro-compound 

Some made by action of HNO s on hydrocarbon, as nitro- 
benzene. 

Nitro-compounds contain N0 2 . Nitroso derivatives contain, 
NO. Iso-nitroso derivatives contain, = N — OH. 



326 TEXT-BOOK OF CHEMISTRY 



AROMATIC HYDROCARBONS OR BENZENE 
SERIES. 

Having studied the fatty, or open chain, hydrocarbons and 
their derivatives, we now take up the second of the two great 
divisions of organic bodies, viz., the aromatic hydrocarbons. 
These are called aromatic, because of the decidedly aromatic, 
and often pleasant, odor which many of them possess. 

Differences between aromatic and fatty compounds. Aro- 
matic hydrocarbons contain a large percentage of carbon, they 
usually have antiseptic properties, they are not foods. The 
substitution derivatives with nitric acid, sulphuric acid and 
bromine are easily formed and are quite stable, and the 
phenols, or alcohols, have an acid character and do not oxidize 
to form aldehydes. The amines are feebly basic. In all these 
respects aromatic hydrocarbons differ greatly from the fatty 
group. The members of one group cannot be converted into 
those of the other without an entire decomposition and recon- 
struction of the molecule, and, many times, this change cannot 
be accomplished at all. 

Source. The great source of aromatic hydrocarbons is 
found in coal-tar, but they are formed also by the destructive 
distillation of other substances. Some of these bodies are 
formed in plants and may be obtained from the vegetable king- 
dom. 

Constitution. No aromatic compound has less than six car- 
bon atoms, and these are often referred to as the nucleus. The 
nucleus of the compound persists as a unit in spite of the 
other chemical changes which may take place in the molecule, 
and in this way the aromatic character of the substance is pre- 
served. All the members of this group are derived from ben- 
zene by the replacement of hydrogen. 

In benzene, C 6 H 6 , only one substance can be formed by 



AROMATIC HYDROCARBONS '327 

replacement of a single atom of hydrogen with a given radical, 
and it is therefore assumed that all the hydrogen is alike, or, 
in other words, that all the hydrogen atoms are similarly linked 
in the molecule. In order to give expression to this chemical 
structure, the molecule of benzene is represented by the graphic 
formula for the benzene ring, thus : 

H 

I 
H C H 



C C 

II I 

c c 

H C H 

I 
H 

In this formula, it will be seen that the carbon atoms are 
linked in a closed chain, alternately by one and two points of 
attraction, leaving one for the attachment of a hydrogen atom. 
It will be seen further, that all the hydrogen is similarly linked, 
and as a result, when one atom is replaced by a given radical 
the same compound is always formed. 

Such is not the case, however, when two hydrogen atoms 
of the ring are replaced by a given radical : in such an instance, 
the substance formed is capable of existing in three isomeric 
modifications, which seem to be dependent upon the relative 
positions of the replacing radicals. These three isomeric forms 
are named, Ortho-, Meta-, and Para-, indicating different rel- 
ative positions in the benzene ring. When we replace two 
hydrogen atoms in the ring by two hydroxyl radicals, three 
isomeric forms result, the structure and names of which are 
given in the formulae, thus : 



328 TEXT-BOOK OF CHEMISTRY 

H H H 

I I I 



I I I 

c c c 

/^ /^ /^ 

H— C C— O— H H— C C— H H— C C— H 

I! I II I II I 

H— C C— H H— C C— O— H H— C C— H 

\S \S \S 

c c c 

I I I 

H H O 

I 
H 

Ortho-position. Meta-position. Para-position. 

Ortho-di-hydroxy Meta-di-hydroxy Para-di-hydroxy 

benzene benzene benzene 

BENZENE SERIES. 

The members here form an homologous series represented 
by the general formula, C n H 2n _ 6 . They are formed by replace- 
ment of hydrogen in benzene by the radical methyl, CH 3 . 
Their names and structure are given in the following table: 

Table of Aromatic Hydrocarbons. 

Benzene C 6 H 6 . 

Toluene C 6 H 5 CH 3 or C 7 H 8 . 

Xylene C 6 H 4 (CH 3 ) 2 or C 8 H 10 . 

Cumene C 6 H3(CH 3 )3 or C 9 H X2 . 

Tetra-methyl benzene C 6 H 2 (CH 3 )4 or GoHu. 

Penta-methyl benzene C 6 H(CH 3 ) 5 or CuHi 6 . 

Hexa-methyl benzene C 6 (CH 3 ) 6 or G2H18. 

Many of these hydrocarbons occur in isomeric forms, thus 
greatly increasing their number. 

The formation of derivatives of aromatic hydrocarbons fol- 
lows the same rules that apply to the fatty group. Aromatic 
alcohols, aldehydes, acids, ethers and compound ethers are 
formed by replacement of hydrogen of the benzene nucleus by 
the appropriate radical, in each case. These chemical changes 
are usually accomplished, however, by indirect methods. 



BEXZEXE SERIES 329 

A benzene nucleus containing the marsh gas radical, CH 3 , 
such as is seen in toluene, xylene, "&c, partakes somewhat of 
the nature of a fatty hydrocarbon, because of the presence of 
this radical. The fatty portion, or side chain, of such a mole- 
cule, is capable of being oxidized into an alcohol, aldehyde and 
acid, as may be seen from the equations : 

CeHsCHs C 6 H 5 CH 2 OH C 3 H 5 CHO C s H 5 CH0 2 . 

Hydrocarbon Benzyl alcohol Benzoic aldehyde Benzoic acid 

Benzene, Benzol, C 6 H 6 . 

Preparation. By distillation of coal-tar, products lightef 
and heavier than water are obtained, and these are separated 
by passing into water. Benzene is obtained by distillation of 
the " light oil," after it has been treated with caustic soda and 
sulphuric acid. 

Benzene can be prepared, pure, by distilling a mixture of 
benzoic acid and calcium hydroxide, according to the equation : 

GJtHCOi + Ca(OH) a = CaC0 3 -f H 2 -f OH* 

Properties. A colorless, volatile, inflammable liquid ; pecu- 
liar ethereal odor ; specific gravity, .884 ; boiling point, 80 ° ; 
solidifies at o° ; insoluble in water. Benzene is a solvent for 
resins, fats, oils and many other bodies. 

Toluene, Methyl Benzene, C 6 H 5 CH 3 , or C 7 H S . 

Toluene is found in coal-tar : it may be obtained by the dry 
distillation of balsam tolu. 

Preparation of the members of the benzene series consists in 

heating the bromide of a given member of the series with the 

bromide of methyl and metallic sodium, when the next higher 

member of the series will be formed. This reaction may be 

utilized for the preparation of toluene, and is shown in the 

equation : 

C 6 H 5 Br + CH 3 Br + Xa 2 = C 6 H 5 CH 3 + 2NaBr. 

In properties, toluene shows some resemblance to fatty com- 
pounds, on account of the presence of the methyl radical. This 
radical is capable of being oxidized to benzoic acid. 



330 TEXT-BOOK OF CHEMISTRY 

Toluene is a clear, volatile liquid, much like benzene. It 
boils at in , and does not solidify at o° — differing from ben- 
zene in these respects. 

Xylene, Dimethyl Benzene, C 6 H 4 (CH 3 ) 2 , is found in coal- 
tar. The ortho-, meta-, and para-forms are known. 

Xylene is made from toluene by a reaction similar to the 
above, thus : 

C 6 H 4 CH 3 Br + CH 3 Br + Na 2 = C 6 H 4 (CH 3 ) 2 + 2NaBr. 

Xylene is a clear, colorless, volatile liquid : it yields phthalic 
acid, C 6 H 4 (HC0 2 ) 2 , by oxidation. 

Cymene, C 6 H 4 CH 3 C 3 H 7 , or C 10 H 14 . {Para-methyl- propyl 
benzene.) 

Cymene is found in the oil of thyme : it has been made by 
synthetic means. 

This compound is a liquid, of pleasant odor, which boils at 
1 75° ; it is closely related to the terpenes, from which it may be 
obtained by heating with phosphoric oxide. 

TERPENES, CioHw. 

The terpenes constitute a class of isomeric hydrocarbons, 
formed by direct union of hydrogen to cymene. They are well 
known as the essential oils of juniper, turpentine, lemon, berga- 
mot, &c. They possess strong antiseptic properties. 

The terpenes undergo polymeric change with great ease by 
heating in closed tubes, or by the action of sulphuric acid. 
Sometimes this change occurs spontaneously, an example of 
which is seen in the conversion of oil of lemon into oil of tur- 
pentine by long standing. 

Oxygen and hydrochloric acid combine directly with the 
terpenes: bromine and iodine, by dehydration, convert them 
into cymene. 

Oil of Turpentine is obtained by distillation of the resin of 
various species of Finns with steam. 



TERPENES 331 

Properties. A clear, colorless, thin, inflammable liquid ; of 
characteristic, aromatic odor, burning taste ; specific gravity, 
0.855 5 boiling point, 160 ; nearly insoluble in water ; soluble 
in alcohol and ether ; dissolves resins, oils, phosphorus, sulphur. 
When hydrochloric acid gas is passed through it, artificial 
camphor, C 10 H 16 HC1, separates as a solid. 

Terebene is an optically inactive polymeric modification of 
above. Made by mixing turpentine with sulphuric acid and 
distilling; treating distillate with soda, and redistilling at 160 . 

Resins are oxidized hydrocarbons, obtained from plants ; 
they are divided, pharmaceutically, into oleo-resins, gam-resins, 
and balsams. 

Oleo-resins contain resin and oil ; gum-resins contain muci- 
lage and oil ; balsams are resinous bodies containing benzoic 
acid. 

Properties. Resins are amorphous, brittle, insoluble in 
water, soluble in alcohol, ether and oils ; they liquefy by heat, 
but decompose before volatilizing; they show the character of 
acids. 

India rubber, or caoutchouc, is the dried milky juice of cer- 
tain tropical plants. It consists of a mixture of hydrocarbons, 
chiefly, C 20 H 32 , C 10 H 16 , C 5 H 8 . Properties. Yellowish-brown ; 
hard and tough when cold ; insoluble in water and alcohol ; 
soluble in ether, chloroform, bisulphide of carbon, and benzene. 
When heated, melts to thick liquid at 180 , and when cooled, 
remains soft and sticky for some time. 

Vulcanised rubber contains seven to ten per cent, of sulphur. 
More elastic and flexible than crude form. 

Hard rubber contains twenty to thirty-five per cent, sulphur, 
and sometimes a little white lead. Hard, tough, and capable 
of taking high polish. 

Gutta percha. Dried juice of Isonandra gutta. Much like 
india-rubber. Properties. Hard, yellowish-brown, solid; 



332 TEXT-BOOK OF CHEMISTRY 

softens when heated; insoluble in water, alcohol, dilute acids, 
and alkalies; soluble in turpentine, bisulphide of carbon and 
chloroform. 

Stearoptens or Camphors. Obtained by incising certain 
topical plants (Cinnamomum camphorum) . Chemically, much 
like terpenes, but have oxygen in the molecule. Composi- 
tion: 

CioHisO and GoHieO. 

Properties. White, tough, crystalline masses ; pleasant, char- 
acteristic odor ; volatile ; acts as a poison ; soluble in alcohol, 
ether, chloroform, carbon bisulphide and oils ; only slightly 
soluble in water. When heated with HN0 3 forms camphoric 
acid, C 8 H 14 (HC0 2 ) 2 , a colorless, crystalline body, of acrid taste. 

Camphor may be reduced to powder by the addition of a few 
drops of ether or alcohol. 

Monobromated Camphor, C 10 H 15 BrO. Made by boiling 
camphor with bromine. 

Properties. White, volatile, crystalline solid ; odor and taste 
of camphor. 

Menthol, Mint Camphor, C 10 H 19 OH. Occurrence in oil 
of peppermint, from which it separates on standing. 

Properties. Clear crystals ; nearly insoluble in water ; soluble 
in alcohol ; odor of peppermint ; cooling, pungent taste. 

Thymol, C 10 H 14 O, or C 6 H 3 CH 3 C 3 H 7 OH (Methyl— propyl— 
phenol). Found in oil of thyme. 

Properties. Colorless, crystalline solid ; odor of thyme ; burn- 
ing taste ; melts at 50 ° ; boils at 230 ; nearly insoluble in water ; 
soluble in alcohol. Used as an antiseptic. 

Eucalyptol, C 10 H 18 O. Found in the volatile oil of Eucalyp- 
tus globulus and other species of eucalyptus. A colorless, aro- 
matic, oily liquid. 






PHENOLS AND PHENOL DERIVATIVES '333 

PHENOLS AND PHENOL DERIVATIVES. 

Definition of Phenols. Compounds formed by replacement 
of hydrogen of benzene by hydroxyl. Mono-, di- and tri- 
atomic, &c, like the fatty alcohols. Differ from latter by not 
forming aldehydes, or acids by oxidation. 

Carbolic Acid, Phenol, Phenyl hydrate, Phenyl alcohol, 
C 6 H 5 OH. Crude acid obtained by distilling coal-tar at 170 to 
190 ; contains phenol, cresol and impurities. A reddish-brown 
liquid of disagreeable odor. Pure acid obtained by fractional 
distillation of crude variety. 

Properties. Colorless, deliquescent, needle-shaped crystals, 
turning pink and then brown by long exposure; characteristic 
aromatic odor; corrosive, anaesthetic local action. By adding 
five per cent, of water converted into clear liquid; soluble in 
twenty parts water, in alcohol, glycerine, ether, chloroform and 
oils; melts at 35 ; boils at 188 ; specific gravity 1.065. An 
alcohol in chemical structure, but the hydrogen of the hydroxyl 
is replaceable by some metals ; as by action of caustic potash or 
caustic soda to form phenolate of sodium, or potassium. 

Largely used as an antiseptic. Acts as a poison. Antidote : 
Solution of sodium sulphate ; mucilaginous drinks ; stimulants. 

Tests. 
(Use an aqueous solution.) 

1. Coagulates albumen and collodion. 

2. Colors neutral solution of ferric chloride intensely and 
permanently violet-blue. 

3. White precipitate with bromine water, of tribrom-phenol, 
C 6 H 2 Br 3 OH. 

4. Turns yellow on heating with nitric acid. 

Creosote. Coal-tar creosote is chiefly carbolic acid. Official 
creosote is obtained from wood-tar, and best from beechwood- 
tar. Shows great resemblance- to carbolic acid. Consists chiefly 
of guaiacol, C 7 H 8 2 , and creosol, C 8 H 10 O 2 . 



334 TEXT-BOOK OF CHEMISTRY 

Creosote is distinguished from carbolic acid by being less 
soluble in water (i in 150), not coagulating collodion, not 
solidifying on cooling, and by high boiling point (205 to 

215°)'. 

Guaiacol, C 6 H 4 OH.O(CH 3 ). A colorless liquid, strong, 
aromatic odor; soluble in alcohol, an<jl ether. (Creosol, C 6 H 3 . 
CH 3 .OH.O(CH 3 ) or C 7 H 6 (OH) (O.CH 8 ).) 

Sulphocarbolic acid, Sozolic acid, Aseptol, Phenol-sulphonic 
acid, C 6 H 4 HS0 3 OH. 

Prepared by dissolving carbolic acid in strong sulphuric acid. 

The sodium salt is made by dissolving Na 2 CO s in the acid, 
when the hydrogen of HSO s is replaced by sodium, thus : 
C 6 H 4 NaS0 3 OH. 

A white, soluble crystalline salt. 

Sulphonic acid is viewed as formed from H 2 S0 3 , by replacing 
one hydrogen atom by organic radicals. 

Ichthyol is a brown, tar-like liquid, having a disagreeable 
odor ; it is obtained by distilling a mineral found in the Tyrol. 

Resorcin, Resorcinol, Meta-dihydroxy-benzene, C 6 H 4 - 
(OH) 2 . A diatomic phenol. Formed by fusing resins, as, 
galbanum and asafoetida, with caustic alkalies. May be made 
synthetically from benzene. 

Properties. White, or reddish-brown, crystalline powder, 
soluble in water, sweetish taste ; fuses at 118 ; boils at 2j6° . 

Pyrogallic Acid, Pyrogallol, C 6 H 3 (OH) 3 . Prepared by 
heating gallic acid to 200 , when C0 2 escapes. 

Properties. Forms colorless, needle-shaped crystals ; melts 
at 1 3 1 ° ; soluble in water, ether and alcohol. Alkaline solutions 
of pyrogallic acid absorb oxygen, and turn red, then brown. 
Gives a yellow color with nitric acid, which turns brown. Acts 
as a strong reducing agent. 

Oil of Bitter Almonds, Benzaldehyde, C 6 H 5 COH. Easily 
oxidized to benzoic acid. Does not occur free. 



PHENOLS AND PHENOL DERIVATIVES * 335 

Formed by fermentation of amygdalin, a glucoside, found in 
bitter almonds, wild cherry, kernels of peaches, &c, by action 
of ferment emulsin, in presence of water ; forming, glucose, oil 
of bitter almonds and hydrocyanic acid. 

Prepared by maceration of bitter almonds with water, and 
distilling, and thus contains hydrocyanic acid. 

Properties. Colorless, oily liquid, of peculiar odor. Poison- 
ous properties due to presence of HCN. Bitter almond water 
has one part oil bitter almonds to 999 of water. 

Benzoic Acid, C 6 H 5 C0 2 H, or H.C 7 H 5 2 . 

Occurrence in nature in resinous substances, called balsams, 
and in the urine of herbivorous animals. 

Preparation. From the resins by distillation. Artificial 
preparation, by action of chlorine upon warm toluene, to form 
tri-chlormethyl-benzene, and action of water, under pressure, 
upon this compound, thus : 

C 6 H 5 CH 3 + 6C1 = C 6 H 5 CC1 3 + 3HCI, 
C 6 H 5 CC1 3 + 2H 2 = C 6 H 5 C0 2 H + 3HCI. 

Properties. White, shining, scaly crystals ; slight aromatic 
odor of benzoin ; acid reaction ; slightly soluble in water ; solu- 
ble in ether, alcohol and oils. 

Neutralized with an alkali and treated with neutral ferric 
chloride, forms a reddish precipitate. 

Ammonium, Sodium and Lithium Benzoate. Formed by 
neutralizing benzoic acid with ammonium and sodium hydrox- 
ide, and lithium carbonate. All three are white, soluble salts. 

Phthalic Acid, C 6 H 4 (C0 2 H) 2 . A dibasic aromatic acid. 
Formed when ortho-xylene, C 6 H 4 (CH 3 ) 2 , is oxidized by nitric 
acid, or potassium permanganate. Occurs in short, prismatic 
crystals; soluble in water, alcohol and ether. It melts at 184°, 
and when heated above this point it loses water and is converted 
into the anhydride, according to the equation : 

CeH4(CQ 2 H) 2 — H 2 = CeHiCaOs. 



336 TEXT-BOOK OF CHEMISTRY 

Phthalic anhydride, by action of phenol and sulphuric acid, 
forms phenol-phthalein, thus : 

C S H 4 3 + 2C 6 H 5 OH = H 2 + C 20 H 14 O 4 . 

Phenol-phthdlein forms colorless, needle-shaped crystals; in- 
soluble in water, soluble in alcohol. Solution of this salt is 
purplish-red in alkaline medium, colorless in acids. It is used 
as an indicator in analysis. 

Phenol acids contain at least one OH radical attached to 
the benzene ring, and carboxyl in addition. They are called 
oxyacids, because of the additional oxygen of this hydroxyl. 

Salicylic acid, Oxybenzoic acid, C 6 H 4 (OH) (C0 2 H), or 
H.C 7 H 5 3 . 

Occurrence in Nature. As methyl ester, in oils of winter- 
green, and birch. May be obtained by fusing caustic potash 
with indigo, or salicin. 

Preparation. By first forming sodium phenolate, thus : 

C 6 H 5 OH + NaOH = C 6 H 5 ONa + H 2 0. 

The sodium phenolate is dried and acted upon by C0 2 , in 
closed vessels, at temperature of 130 , and the resulting com- 
pound is treated with hydrochloric acid, as shown in the 
equations : 

2C 6 H 5 ONa + C0 2 = C 6 H 4 NaOC0 2 Na + C 6 H 5 OH. 
C 6 H 5 ONaC0 2 Na + 2HCI = C 6 H 4 OHC0 2 H + 2NaCl. 

Properties. Fine, needle-shaped crystals, white color, 
sweetish acrid taste, acid reaction. Slightly soluble in water ; 
soluble in alcohol and ether. Fuses at 158 ; volatilized in a 
current of steam, or at 200 . Use as antiseptic and preservative. 

Tests. 

1. Solution with ferric chloride gives violet color. 

2. Cupric sulphate gives green color. 

3. Dissolve in methyl alcohol, and add one-fourth volume 



PHENOLS AND PHENOL DERIVATIVES 337 

sulphuric acid, and heat; odor of methyl salicylate develops. 

Sodium Salicylate is obtained by dissolving sodium hydrox- 
ide in salicylic acid. It is a soluble salt, of sweetish taste, and 
is much used in medicine. 

Methyl Salicylate, CH 3 C 7 H 5 3 . Occurs as oil of winter- 
green, in Gaultheria procumbens. Made by heating salicylic 
acid, methyl alcohol, and sulphuric acid together. It is a clear 
liquid, of fragrant odor. 

Phenyl Salicylate, Salol, C 6 H 5 C 7 H 5 3 . Made by heating 
together sodium phenolate, sodium salicylate, and phosphorus 
oxychloride. 

Properties. A white, crystalline powder ; nearly insoluble in 
water; soluble in ether, alcohol, benzene and oils (fatty and 
essential) ; peculiar odor, slight taste; fuses at 42 °. Used as 
antiseptic, analgesic, and antipyretic. 

Salol is decomposed, with liberation of phenol, by action of 
caustic potash. 

Gallic Acid {Trioxy-benzoic acid), C 6 H 2 (OH) 3 C0 2 H, or 
H.C 7 H 5 O s . 

Prepared from nut-galls by moistening and exposing to the 
air for about six weeks, for fermentation, in which tannic acid 
is converted into gallic acid, extracting the mass with boiling 
water, and crystallizing. May be obtained from tannic acid by 
boiling with diluted acids or alkalies. 

Properties. A white solid, in silky, needle-shaped crystals ; 
astringent, acid taste, acid reaction ; soluble in one hundred 
parts cold, three parts hot water ; soluble in alcohol, only slightly 
soluble in ether and chloroform. 

Tests. 

1. Gives a bluish-black precipitate with ferric salts. 

2. Does not coagulate albumen nor precipitate alkaloids, gela- 
tine or starch. 

23 



338 TEXT-BOOK OF CHEMISTRY 

3. With potassium cyanide gives a rose color. 
Tannic Acid, C 14 H 10 O 9 . (Digallic acid.) Chemical struc- 
ture represented by the graphic formula. 

H H 

I I 

O 

H I H H I H 

x o c o / x o c o x 

\/ %y \/ \y 

c c c c 

II I II I 

C C C — O — c c c 

/\ // II II \ yf\ 

H C C H 

1 I 
H H 

Occurrence in Nature. Tannic acid occurs in many plants, 
in varying forms, but it is usually obtained from nut-galls. 

Preparation. By extracting powdered nut-galls with com- 
mercial ether, and allowing the acid to crystallize from the 
solution. 

Properties. Light-yellowish, amorphous powder, or scales, 
very astringent ; acid reaction ; freely soluble in water. When 
boiled with dilute alkalies or acids it forms gallic acid, by 
taking up water. 

Tests. 

1. Ferric chloride gives bluish-black precipitate, soluble in 
excess with greenish color. 

2. Solution caustic potash gives brown color. 

3. In weak solution with lime water, a white precipitate 
forms, which turns blue with excess of Ca(OH) 2 . 

4. Precipitated by gelatine, tartar-emetic, albumen, or alka- 
loids. 

NITROGEN COMPOUNDS OF BENZENE. 
The Nitro-derivatives of Benzene are formed by the action 
of strong nitric acid upon the aromatic hydrocarbons, by which 



NITROGEN COMPOUNDS OF BENZENE 339 

means the hydrogen of the benzene ring is replaced by the 
radical N0 2 . These compounds usually enter into solution in 
the strong nitric acid causing their formation, and may be 
precipitated by the addition of water. This action of nitric 
acid may be represented thus : 

C 6 H 6 + N0 2 OH = C s H B N0 2 + H 2 0. 

Benzene Nitric acid Nitrobenzene 

C 6 H 5 CH3 + N0 2 OH = C 6 H 4 N0 2 CH 3 + H 2 0. 

Toluene Nitro-toluene 

These compounds are named mono-, di- and tri-nitro com- 
pounds, &c, according to the number of the replacing radicals. 

This replacement of hydrogen takes place in the hydrogen of 
the benzene nucleus, and not in the side group. The number 
of the replacing radicals depends upon the strength of the acid 
and the length of time it is allowed to act. 

General Properties. The nitro-compounds are usually pale- 
yellow or yellowish liquids, that can be distilled in a cur- 
rent of steam; or, as is the case with the higher derivatives, 
yellow, needle-shaped or prismatic crystals ; heavier than water 
and insoluble, but soluble in alcohol, ether and strong acetic 
acid. 

All the nitro-compounds are reduced by the action of nascent 
hydrogen, in acid solution, to the corresponding amido com- 
pounds, in which hydrogen takes the place of oxygen ; thus, 
C 6 H 5 N0 2 becomes C 6 H 5 NH 2 . This change may be effected by 
the action of tin on hydrochloric acid, in the presence of the 
nitro-derivatives. They are largely used for making amido- 
compounds. 

Nitro-benzene, C 6 H 5 N0 2 . Formed by adding benzene, 
slowly, to cooled nitric acid as long as the hydrocarbon seems 
to dissolve. After standing for some time, the nitro-benzene 
is separated by adding water, washing with water and with 
weak caustic soda, and distilling with steam. 



340 TEXT-BOOK OF CHEMISTRY 

Properties. A light-yellowish liquid, with an odor of bitter 
almonds ; boils at 205 °, and crystallizes at 3 . Used for making 
aniline, or phenyl-amine, and as perfumery for soap by the 
name, essence of mirbane. Highly poisonous. 

Antidote : Empty the stomach and use ammonium carbonate, 
or aromatic spirit of ammonium, cold to the head and electricity. 

Dinitro-benzene, C 6 H 4 (N0 2 ) 2 , is formed when benzene is 
added to a mixture of nitric and sulphuric acids and heated to 
boiling. It is solid and crystalline. 

Trinitrophenol, C 6 H 2 (N0 2 ) 3 OH. (Picric acid, carbazotic 
acid.) Not a true nitro-benzene, but a nitro-phenol. Mono- 
and di-nitro-phenols known, but this is the only important one. 
Formed by action of fuming nitric acid on many organic bodies, 
as indigo, silk, leather, wool, &c. 

Prepared, usually, by slowly adding carbolic acid to fuming 
nitric acid. 

Properties. It forms pale-yellow scales, or needles. It is 
slightly soluble in water, alcohol, and ether. It melts at 122.5 °, 
and can be sublimed when carefully heated, but when rapidly 
heated explodes. Some of its salts form beautiful crystals, but 
they are very explosive by heat or concussion. It is used as 
a yellow dye for silk and wool ; is poisonous when taken inter- 
nally in sufficient dose. 

AMIDO DERIVATIVES OF BENZENE. 

It is necessary to remember, in studying these compounds, 
that they may be looked upon from two points of view : First, 
as benzene in which one or more of the hydrogen atoms have 
been replaced by the radical, NH 2 , when the name would be 
amido-benzene; second, as ammonia in which one, two or all 
three hydrogen atoms have been replaced by the radical, C 6 H 5 , 
and named phenyl-amine. Furthermore, they are named mon- 
amines, di-. tri-, tetra-amines, &c, according to the number of 



AMIDO DERIVATIVES OF BENZENE 34 1 

the radical NH 2 ; or primary, secondary and tertiary amines, 
according to the number of C 6 H 5 , replacing hydrogen in ammo- 
nia (NH 3 ). For example, phenyl-amine, C 6 H 5 NH 2 , is a pri- 
mary amine; diphenyl-amine, (C 6 H 5 ) 2 NH, is a secondary 
amine, &c. 

Aniline, Phenyl-amine, QH 5 NH 2 , is a primary monamine 
— primary, because of one C 6 H 5 ; monamine, because of one 
NH 2 . First obtained by dry distillation of indigo. Occurs in 
coal-tar, and bone-oil. 

Prepared by action of nascent hydrogen on nitro-benzene, 
C 6 H 5 N0 2 , when hydrogen replaces the oxygen to form 
QH 5 NH 2 . 

Properties. A colorless, oily liquid ; turning yellow or brown 
on exposure to air. Peculiar odor, bitter taste; poisonous. 
Slightly alkaline and combines with acids, with retention of 
hydrogen like ammonia, to form salts. 

Aniline dyes are made from impure aniline containing tolui- 
dine, by the action of oxidizing agents, as arsenous, and arsenic 
oxides, chromic or nitric acid or hypochlorites, forming the 
various beautifully colored compounds. 

Diphenyl-amine, (C 6 H 5 ) 2 NH, is a secondary monamine, 
obtained by destructive distillation of tri-phenyl-rosaniline (or 
aniline blue). 

Properties. White scales, having an agreeable odor of flow- 
ers, and a burning, aromatic taste. It is nearly insoluble in 
water, soluble in alcohol, ether and petroleum naphtha. Dis- 
solved in strong sulphuric acid, it is colored blue by nitric or 
nitrous acid, and is used as a reagent in water analysis. 

Meta-phenyl-diamine, C 6 H 4 (NH 2 ) 2 . Made by the action 
of reducing agents on meta-dinitro-benzene. Forms grayish 
crystals ; nearly insoluble in water ; soluble in alcohol and ether. 
Basic properties. Forms a yellow color, with traces of nitrous 
acid. Used as reagent. 



34 2 TEXT-BOOK OF CHEMISTRY 

Sulphanilic Acid, Aniline-par a-sulphonic acid, C 6 H 4 NH 2 - 
S0 3 H. Made by heating aniline with fuming sulphuric acid. 
A colorless, crystalline solid ; slightly soluble in water. It is 
used in obtaining the diazo-reaction in urine of typhoid fever, 
measles and tuberculosis. This test is applied by dissolving the 
above compound in water and hydrochloric acid and adding to 
urine, and then adding NaN0 2 solution, and ammonia. Nor- 
mal urine, yellow ; in above diseases, red color forms. Presence 
of phenol, gives a red color. 

Acetanilide, Antifebrine, Phenyl-acetamide, C 6 H 5 NHC 2 - 
H 3 0. Anilides are formed by replacement of hydrogen of 
amidogen in the amido-compounds, by alcohol or acid radicals. 
Named alcohol-anilides and acid-anilides. 

Preparation. By boiling aniline with glacial acetic acid in 
such a manner that the vapors are recondensed, for two days, 
until a drop taken out solidifies on cooling. The product is 
then subjected to fractional distillation, when water first distills 
off, and that which comes over at 295 ° is collected. 

Properties. Colorless, odorless, scaly crystals ; nearly in- 
soluble in cold water ; soluble in hot water, alcohol and ether ; 
neutral in reaction. It is decomposed by hydrochloric acid to 
aniline and acetic acid. 

Exalgin, M ethyl-ace tanilide, C 6 H 5 N.CH 3 .C 2 H 3 0. Made 
by the action of methyl iodide upon sodium acetanilide. 

Properties. Crystalline needles ; nearly insoluble in water ; 
soluble in alcohol ; fuses at ioo° ; boils at 250 . 

Benzanilide, C 6 H 5 CO.NHC 6 H 5 , is sometimes used in medi- 
cine. 

Amido-phenols, C 6 H 4 .OH.NH 2 , are formed by the action of 
reducing agents (H) on the corresponding nitro-phenol (C 6 H 4 - 
OHN0 2 ), when hydrogen takes the place of oxygen. The 
ethyl ethers of amido-phenols, formed by replacing hydrogen 
of the hydroxyl by C 2 H 5 — C 6 H 4 O.C 2 H 5 NH 2 — , are called 






AMIDO DERIVATIVES OF BENZENE . 343 

" phenetidines." When para-phenetidin, C 6 H 4 OC 2 H 5 NH 2 , is 
treated with glacial acetic acid, the radical of this acid is intro- 
duced, taking the place of hydrogen in amidogen, and forming 
para-acet-phenetidin (C 6 H 4 OC 2 H 5 NHC 2 H 3 0). This com- 
pound is used in medicine under the name phenacetine. 

Properties. It forms white, lustrous crystals ; odorless and 
tasteless ; nearly insoluble in water ; soluble in alcohol. 

Diazo and Azo compounds contain the radical, — N = N — . 
In the diazo compounds this radical links together a hydro- 
carbon radical and an acid radical, thus : C 6 H 5 — N = N — CI, 
diazo-benzene chloride. In azo compounds it links two hydro- 
carbon radicals together, thus : C 6 H 5 — N = N — C 6 H 5 , azo- 
benzene. 

Diazo-compounds are formed by the action of nitrous acid 
upon aromatic amines, in acid solution : 

C 6 H 5 NH 2 HC1 + OHNO = C 6 H 5 N 2 C1 + 2H 2 0. 

They are colorless, crystalline, and sometimes explosive. 
Soluble in water ; insoluble in ether. 

Hydrazines are derivatives of hydrazine, or N 2 H 4 , or 
NH 2 NH 2 , 

H H 

\ / 

N — N: 

/ \ 

H H 

Formed from it by replacement of hydrogen by hydrocarbon 
radicals. 

Phenyl Hydrazine, C 6 H 5 NH-NH 2 . Prepared by reduction 
of diazo-benzene chloride, by nascent hydrogen : 

C 6 H 5 N 2 C1 + 2H 2 = C 6 H 5 N 2 H 3 .HC1. 

Diazo-benzene Phenyl Hydrazine 

chloride hydrochloride 

Properties. A colorless, crystalline solid; fuses at 23 ° to an 
oily liquid. It is strongly basic, a powerful reducing agent, 
and reduces Fehling's solution in the cold. It is used as a re- 



344 TEXT-BOOK OF CHEMISTRY 

agent, as it combines with aldehydes and ketones, and hence, 
with sugars, to form crystalline compounds known as hydra- 
zones and osazones; used also in making antipyrine. 

Saccharine, Anhydro-ortho-sulphamine-benzoic Acid, C 6 - 
H 4 CO.S0 2 NH. Formed from benzoic acid, C 6 H 5 C0 2 H, by 
elimination of water and introduction of the radicals S0 2 , and 
NH. Two hydrogen atoms of ammonia, and two hydrogen 
atoms of benzene, are replaced by S0 2 and CO, thus : 

H 

I 
H C O 

VX II 

c c— s 

!i I l >-» 

c c— c 

/\// II 

H C O 

I 
H 

Properties. A white powder, slightly soluble in water (solu- 
tion acid reaction), soluble in alcohol and ether. Slight odor 
of bitter almonds, very sweet taste; 280 times sweeter than 
cane-sugar. 

Antipyrine, Phenyl-dimethyl-pyrazalon, C 1;L H 12 N 2 0. 

Properties. A white, crystalline bitter powder ; freely solu- 
ble in water and alcohol. Forms a green, poisonous compound 
with nitrous acid, the same change taking place, after a time, 
with " sweet spirit of nitre." 

COMPOUNDS WITH CONDENSED BENZENE NUCLEI. 

In the aromatic hydrocarbons hitherto considered the single, 
or uncondensed, benzene molecule has formed the nucleus, the 
general formula of which is C n H 2n _ 6 . Other aromatic hydro- 
carbons are well known, in which two and three benzene 
molecules are condensed into a single nucleus. These com- 
pounds are distilled at the higher boiling point of coal-tar ; they 
contain a large percentage of carbon as compared to the hydro- 



COMPOUNDS WITH CONDENSED BENZENE NUCLEI ' 345 

gen; and they form two homologous series. The compounds 
forming these series are Naphthalene and Anthracene ; and both 
of them may be regarded as derivatives of benzene, since by 
their oxidation, phthalic acid and benzoic acid are formed, re- 
spectively. 

Naphthalene, Coal-tar Camphor, C 10 H 8 , forms the homo- 
logous series of hydrocarbons having the general formula 
C n H 2n _ 12 , by replacement of its hydrogen with the radical 
methyl, CH 3 . 

The molecular structure of naphthalene is that of a double 
condensed benzene ring, in which two carbon atoms are com- 
mon to both rings. This structure is shown in the graphic 
formula : 

a. a. 
H H 

I ! 

b. H C C Kb. 

c c c 

II I I 
c c c 

b. H C C H b. 

I I 

H H 

a. a. 

There are two kinds of carbon in the naphthalene molecule : 
one kind is attached to carbon which is found in one ring only ; 
the other kind is attached to carbon which is common to both 
rings. As a result of this structure of the naphthalene nucleus, 
two isomeric forms are produced when hydrogen is replaced 
Dy a single radical ; these are known as the alpha and the beta 
forms. There are four alpha positions, and four beta positions, 
in the naphthalene molecule, and these are represented in the 
above graphic formula by the letters a and b. 

Naphthalene is formed by the destructive distillation of many 
organic bodies. It is prepared by distilling coal-tar at 180 



346 TEXT-BOOK OF CHEMISTRY 

to 220°, treating the product with caustic soda and sulphuric 
acid, and distilling with watery vapor. 

In properties, naphthalene is a white, shining, scaly, crystal- 
line solid ; having a penetrating odor, burning taste ; slightly 
soluble in water ; soluble in alcohol, ether or chloroform. It 
is used in medicine as an intestinal antiseptic, and as an in- 
secticide in the form of " moth-balls." 

Naphthol, Naphtol, C 10 H 7 OH, is the hydroxyl derivative 
of naphthalene. The alpha and beta forms are known. 

B eta-N aphthol is the one used in medicine. It forms shiny, 
crystalline plates ; has the odor of carbolic acid, a burning taste, 
and is soluble in alcohol, ether, chloroform and oils ; only 
slightly soluble in water. 

Santonine, Ci 5 Hi 8 03. While the chemical structure of santonine is 
not understood, it is known to be related to naphthalene. 

Santonine is obtained from Artemisia santonica. It is prepared by 
extracting with alcohol and lime water, and liberating santonine by 
adding an acid. 

Properties. Colorless, prismatic crystals, which turn yellow by ex- 
posure to light; slightly soluble in water; soluble in alcohol or ether; 
colors the urine dark when administered internally. Such urine when 
heated turns red; the red color is destroyed by an acid and restored 
by an alkali. 

Anthracene, C 14 H 10 , forms an homologous series of hydro- 
carbons, having the general formula C w H 2n _ 18 , by replacement 
of its hydrogen by the radical methyl, CH 3 . 

The molecular structure of anthracene is that of three con- 
densed benzene nuclei, as shown in the graphic formula : 

H H H 

I I I 
H C C C H 



c c 

II I 

c c 

H C C C H 

I I I 
H H H 



C C 

I II 

c c 



COMPOUNDS WITH NITROGEN IN THE NUCLEUS - 347 

Anthracene is obtained by the fractional distillation of coal- 
tar above 300 °. 

The pure hydrocarbon occurs in the form of crystalline 
plates, of white color, with a blue fluorescence ; it melts at 212 °, 
and boils at 360 ; it is slightly soluble in alcohol or ether ; 
easily soluble in hot toluene or benzene. 

When anthracene is oxidized, it yields a compound called 
anthraquinone ; reducing agents convert it into anthracene- 
hydride. 

Anthracene is used largely in the preparation of alizarine and 
other artificial coloring agents. 

COMPOUNDS CONTAINING NITROGEN IN THE BENZENE 
NUCLEUS. 

Pyridine Bases. 

By destructive distillation of bones a' tar-like substance is 
formed from the bone gelatine, called bone-oil, or Dippel's 
oil. This liquid furnishes a number of basic substances among 
which are the pyridine bases, some of which can also be 
obtained from coal-tar. 

The pyridine bases form an homologous series, derived from 

pyridine, the names of which are given in the following table : 

j 
Pyridine, C 5 H 5 N, Collidine, C 8 H U N, 

Picoline, C 6 H 7 N, . Parvoline, C9H13N, 

Lutidine, C7H9U, Coridine, G0H15N. 

In properties, these bodies are liquids, of disagreeable pun- 
gent odbr; they resemble ammonia, to which they are closely 
related; and they are capable of forming salts with acids. 

The pyridine bases are separated from bone-oil by shaking 
with sulphuric acid, with which they form salts ; the salts are 
dissolved in water, decomposed by adding caustic soda and 
removed by distillation. 

Pyridine, C 5 H 5 N, is the parent substance of the pyridine 
bases. In chemical structure, it consists of a benzene ring in 



34-8 TEXT-BOOK OF CHEMISTRY 

which a carbon and hydrogen atom have been replaced by 
nitrogen. This structure is shown in the graphic formula, thus : 

H 

I 
H C H 



C C 
H N H 

The other members of the series, given above, are formed 
by replacing hydrogen of the ring by the radical CH 3 . 

Properties. Pyridine is a colorless liquid ; tarry odor ; pun- 
gent taste; boiling point n6° ; specific gravity .98; soluble in 
water ; hygroscopic. It forms salts with acids by direct union 
and retention of hydrogen. 

Pyridine is found in tobacco-smoke, being produced by the 
destructive distillation of tobacco* in smoking. The effect of 
smoking, upon the heart and nervous system, is largely due to 
pyridine absorption. 

It has been used in medicine as a remedy for asthma. 

Naphthalene and anthracene furnish nitrogen derivatives 
analogous in structure to those derived from benzene. They 
are basic bodies obtained from bone-oil and coal-tar. Their 
structure is represented in the following graphic formulas, 
showing the replacement of a hydrogen and a carbon atom in 
naphthalene and anthracene by nitrogen. These nitrogen 
derivatives have been named Quinoline and Acridine. 

H H 

I I 
H C C H 

c c c 

I II I 

c c c 

H C N H 
I 
H 

Quinoline. 



COMPOUNDS WITH NITROGEN IN THE NUCLEUS ' 349 

H H H 

I I I 

H C C C H 



c c 

I II 

c c 



c c 



c c 

H C N C H 

I I 

H H 

Acridine. 



Pyrrole, QH 4 NH, has the molecular structure represented 
in the following graphic formula, thus : 




Pyrrole is a feebly basic liquid, obtained from bone-oil and 
coal-tar. It boils at 130 ; has an odor resembling chloroform, 
and is insoluble in water, but soluble in alcohol, ether or dilute 
acids. It is used for making iodol. 

Iodol, C 4 I 4 NH, is formed from pyrrole by replacing hydro- 
gen with iodine. 

It is prepared by dissolving pyrrole in alcohol, adding iodine, 
and then adding an oxidizing agent. 

Properties. Grayish-brown or yellowish powder ; odorless ; 
tasteless ; soluble in alcohol or ether ; nearly insoluble in water. 
It decomposes at 150 , evolving iodine. 

Iodol is largely used as an odorless substitute for iodoform 
in surgical dressings. 



350 TEXT-BOOK OF CHEMISTRY 

ALKALOIDS. 

Many plants, and especially those having medicinal or poison- 
ous properties, contain basic principles, in which the physio- 
logical properties of the plant reside. These principles are 
feebly alkaline in reaction and are therefore called alkaloids, 
this term meaning alkali-like. 

Alkaloids are feebly basic substances containing nitrogen and 
representing the active principles of plants. In chemical 
nature, they are closely related to pyridine and quinoline, from 
which some of them have been prepared by artificial means. 
Since they all contain the residue of the ammonia radical they 
are regarded as members of the amine and amide group, and 
as such, they may be divided into two classes, viz. : Liquid 
volatile alkaloids, or amines, containing carbon, hydrogen and 
nitrogen ; and solid non-volatile alkaloids, or amides, con- 
taining carbon, hydrogen, nitrogen and oxygen. 

The resemblance of alkaloids to ammonia is clearly shown 
in their basic properties ; their power to combine with acids 
to form salts in which the hydrogen is retained ; their precipi- 
tation with perchloride of platinum, or alkaline potassium- 
mercuric iodide solution. 

In naming the salts of alkaloids, the same rules are followed 
as in other cases, except for the halogen acids. Instead of 
using the terms chloride, bromide, or iodide, for the alkaloidal 
salts of these acids, the terms hydrochloride, hydrobromide 
and hydriodide are employed; therefore, instead of speaking 
of morphine chloride, the term morphine hydrochloride is used. 
The termination irie is used in naming the alkaloids. 1 

The alkaloids are found in all parts of plants, but they occur 
most frequently in the seeds, stems, leaves and bark. Some- 
times a given alkaloid is found in different species of the same 
family of plants, and again, different alkaloids are found in 

1 See U. S. P., 1900. 



ALKALOIDS 3 5 I 

the various parts of the same plant ; in the latter case, however, 
the alkaloids show resemblance in chemical character and 
physiological properties. 

The alkaloids do not usually occur free in nature, but they 
are found as salts with vegetable acids. Morphine occurs com- 
bined with meconic acid ; quinine, with kinic acid, &c. 

General Method of Preparation. The vegetable substance 
is disintegrated and extracted with acidulated water, which 
dissolves out the alkaloid. To this solution is added an alkali, 
which precipitates the alkaloid, and, if it be volatile, it is sepa- 
rated by distillation. If not volatile, the resulting precipitate 
is collected, washed and purified by redissolving in acidulated 
water and reprecipitating, or it may be purified by crystalliz- 
ing from alcohol. 

General Properties. The alkaloids as a class are powerful 
in their physiological action : many of them are intensely 
poisonous, such as strychnine and atropine, while a few are 
comparatively harmless, such as quinine and caffeine. 

Most of the alkaloids have a bitter taste ; the greater number 
are solid non-volatile; some are liquid and volatile, having a 
disagreeable odor ; the solid ones are white and usually crys- 
talline. They have an alkaline reaction, and unite with acids 
to form well defined crystallizable salts. 

The Free Alkaloids are usually insoluble in water, but solu- 
ble in alcohol, ether, chloroform, benzene or acetic ether. The 
alkaloidal salts are usually soluble in water or alcohol, but in- 
soluble in ether, chloroform or benzene. 

General Tests and Precipitants. The alkaloids are precipi- 
tated from solution by the addition of solution of caustic alka- 
lies, tannic acid, picric acid, potassium-mercuric iodide, per- 
chloride of platinum and chloride of gold. 

Mayer s Reagent is made by dissolving 49.8 gm. potassium 
iodide, and 13.546 gm. mercuric chloride, in water to make 
1000 cc. It gives a white, or yellowish precipitate. 



35 2 TEXT-BOOK OF CHEMISTRY 

Iodine Solution, or Wagner's Reagent, is a solution of iodine 
and potassium iodide in water, of convenient strength — about 
20 gm. iodine and 50 gm. iodide of potassium in 1000 cc. of 
water. This reagent gives a red, or reddish-brown precipitate. 

Many of the alkaloids give beautiful color reactions with 
oxidizing agents. 

In Poisoning by Alkaloids, emetics and the stomach-pump 
should be used. Chemical and physiological antidotes are em- 
ployed : the former to produce an insoluble, or harmless com- 
pound, with the alkaloid; the latter to counteract its phys- 
iological action. The general chemical antidote is tannic acid. 

Liquid Volatile Alkaloids. 

Conine, C 8 H 17 N. Source: Conium maculatum (Hemlock). 

Properties. Colorless, oily liquid ; disagreeable odor ; acrid 
taste ; becomes thick and resinous by exposure. Gives vapor to 
air, which forms white fumes with hydrochloric acid, like am- 
monia. 

Sparteine, C 15 H 26 N 2 . Source: Scoparius (Broom top). 

Properties. Colorless, oily liquid. Forms the sulphate by 
union with sulphuric acid ; a crystalline, soluble solid. 

Nicotine, C 10 H 14 N 2 . Source: Obtained from tobacco; the 
leaves of which contain from two to eight per cent. Colorless, 
oily liquid, turns brown. Very poisonous. 

Solid Non- Volatile Alkaloids. 

Opium is the concrete, milky exudation, obtained by incising 
the unripe capsules of Papaver somniferum in the Orient. It 
contains gum, fat, albumen, wax, glucose, volatile matter, 
meconic acid, morphine, codeine and many other alkaloids. 

It should contain not less than 9 per cent, of morphine. 
Dried opium should have 13 to 15 per cent, morphine. 

Deodorized opium is opium exhausted with ether, to remove 






ALKALOIDS - 353 

narcotine, and the weight made up to the original by adding 
sugar of milk. 

Morphine, C 17 H 19 NO s .H 2 0. Properties. Short, transpar- 
ent, white, prismatic crystals ; bitter taste ; soluble in alcohol ; 
slightly soluble in water ; nearly insoluble in ether and chloro- 
form ; alkaline in reaction, and combines with acids to form 
crystalline salts. 

The acetate, hydrochloride and sulphate are used in medi- 
cine; they are white and soluble. 

Apomorphine, made by heating morphine with excess of 
hydrochloric acid under pressure. A white salt, turns green 
when exposed to air. Used as an emetic. 

Tests for Morphine. 

1. With nitric acid, a red color forms; gradually turns yel- 
low. 

2. Blue color with neutral ferric chloride. 

3. Morphine, sugar and sulphuric acid give a red color. 

4. Solutions are precipitated by alkali hydroxides ; soluble in 
excess ; except ammonia water. 

Codeine, C 18 H 21 N0 3 .H 2 0. Properties. White, crystalline 
powder ; soluble in alcohol and chloroform, slightly soluble in 
water. Neutral ; bitter. 

Tests for Codeine. 

1. Solution with chlorine water and ammonia water gives 
yellowish-red color. 

2. Dissolved in sulphuric acid, and warmed with ferric chlo- 
ride, gives deep blue. 

Meconic Acid, C 4 OH(C0 2 H) 3 . Preparation. By extract- 
ing opium with water, neutralizing with CaC0 3 , precipitating 
with CaCl 2 and adding HC1. 

Properties. White, crystalline, soluble in water and alcohol. 
24 



354 TEXT-BOOK OF CHEMISTRY 

Test. 

Ferric chloride gives blood-red color, not affected by mer- 
curic chloride ; thus differing from sulphocyanide of potassium. 
Its presence indicates opium in case of poisoning. 

Cinchona Bark, to be official, must contain not less than five 
per cent, of total alkaloids, and not less than 2.5 per cent, of 
quinine. The alkaloids are in combination with kinic acid. 
It is obtained from various species of cinchona. Its most im- 
portant alkaloids are quinine, quinidine, cinchonine and cin- 
chonidine. 

Quinine, C 20 H 24 N 2 O 2 .3H 2 O. Properties. White, flaky, 
crystalline or amorphous powder permanent in the air; very 
bitter taste. Soluble in alcohol, ether, chloroform, carbon bi- 
sulphide, benzene, ammonia water and dilute acids ; nearly 
insoluble in water. At 125 °, it loses water of crystallization 
and becomes a resinous mass of anhydrous quinine. 

Quinine Sulphate, (C 20 H 24 N 2 O 2 ) 2 H 2 SO 4 .7H 2 O. Formed 
by union of two molecules of quinine with one of sulphuric acid. 

Properties. White, fine, needle-shaped crystals ; absorbs or 
gives up moisture, as air is moist or dry ; very bitter ; soluble 
in alcohol, glycerine ; only slightly soluble in water ; dissolves 
in acidulated water with fluorescence. 

Bisulphate of Quinine is formed when the sulphate is dis- 
solved in excess of sulphuric acid, and contains a molecule of 
the alkaloid united to a molecule of the acid, thus : 

C 20 H 2 4N 2 O 2 .H 2 SO4. 

Properties. Colorless, transparent, needle-shaped crystals; 
soluble in water. 

The Valerianate, Hydrochloride and Hydrobromide are used 
in medicine ; and they are freely soluble in water, except the 
valerianate, which is sparingly soluble. 



ALKALOIDS ' 355 

Tests for Quinine. 

1. Solutions of quinine in acidulated water, with chlorine 
water and ammonia water, give a green color. 

2. The above, to which a crystal of potassium ferrocyanide 
has been added before the ammonia water, gives a pink color 
which soon turns red. 

3. Quinine is precipitated white by ammonia water, but dis- 
solves in excess. 

4. Fluorescence in acid solution by reflected light. 

Quinidine. Isomeric form of quinine, and like it in proper- 
ties. Differs in being precipitated from neutral solution by 
potassium iodide. 

Cinchonine and Cinchonidine are isomeric. Formula, 
C 19 H 22 N 2 0. In properties they are like quinine. Cinchonine 
may be distinguished from quinine by the insolubility of the 
precipitate formed by ammonia water in an excess of the re- 
agent. Cinchonidine does not form fluorescent solutions. 

Strychnine, C 21 H 22 N 2 2 . Source: Found in the seeds and 
bark of Strychnos nux vomica and other varieties of Strych- 
nos, in company with brucine. 

Properties. Colorless, fusible, four-sided, prismatic crystals ; 
intensely bitter taste ; almost insoluble in water ; soluble in 
chloroform and dilute acids. 

The sulphate, phosphate and nitrate are largely used in medi- 
cine, and are more soluble than the alkaloid. Strychnine is a 
most powerful poison. One-quarter grain is the minimum fatal 
dose. 

Tests for Strychnine. 

1. Dissolved in sulphuric acid, and a crystal of bichromate of 
potassium drawn through the solution, gives a beautiful play 
of colors : first blue, then violet, cherry-red, pink and yellow. 
This test is exceedingly delicate. 

2. Precipitated by dilute solution of potassium dichromate. 



356 TEXT-BOOK OF CHEMISTRY 

Brucine, C 23 H 26 N 2 4 4H 2 0. Found with strychnine in 
Strychnos. Properties. Like strychnine — weaker physiolog- 
ically. Gives red color with nitric acid. 

Atropine (Daturine) , C 17 H 23 N0 3 . Source: Atropa bella- 
donna and Datura stramonium. Properties. White, pris- 
matic crystals ; bitter ; dilates pupil. Soluble in alcohol and 
chloroform ; slightly soluble in water. Sulphate frequently used 
in medicine. 

Tests for Atropine. 

i. Dissolve in sulphuric acid, add a crystal of potassium 
bichromate, and a few drops of water ; a green color slowly ap- 
pears, and odor of orange flowers develops. 

2. Action on pupil — dilates. 

Hyoscyamine, C 17 H 23 NO s . Source: Hyoscyamus niger, 
with hyoscine. Shows great resemblance to atropine in prop- 
erties. 

Hyoscine, C 17 H 21 N0 4 , is amorphous. Used in medicine as 
hydrobromide, as sedative and hypnotic. 

Cocaine, C 17 H 21 N0 4 . Source: Leaves of Erythroxylon 
coca contain from .15 to .65 per cent. 

Properties. Shining, prismatic crystals ; slightly soluble in 
water, soluble in alcohol, ether and chloroform. The hydro- 
chloride frequently used in medicine as a powerful local anaes- 
thetic. When heated in sealed tube with acids it decomposes 
to benzoic acid, methyl alcohol, and ecgonine, C 9 H 15 N0 3 . 

Tests for Cocaine. 

1. Perchloride platinum gives yellowish precipitate. 

2. Mercuric chloride gives a white precipitate. 

3. Picric acid gives a yellow precipitate. 

4. Alkali carbonates and hydroxides give a white precipi- 
tate, soluble in excess of ammonia water. 

Aconitine. Source: Aconitum napellus, contains .2 per 
cent. Probably a mixture of several different alkaloids. 



PTOMAINES 357 

Properties. White, or grayish white, powder ; sharp, pun- 
gent taste ; causes tingling sensation and numbness in the mouth 
and throat. A most powerful poison. 

Physostigmine, Eserine, C 15 H 21 N 3 2 . Found in seeds of 
Phy so stigma venenosum, calabar bean. 

Properties. Difficult to crystallize ; nearly tasteless ; gradu- 
ally turns red. Sulphate and salicylate used in medicine, for- 
mer, easily soluble; latter, only slightly souble. 

Caffeine, C 5 H(CH 3 ) 3 N 4 2 . (Trimethyl xanthine.) 
Source: Coffee, tea. 

Properties. Light, white, slender, long, flexible crystals ; 
soluble in 80 parts water and 33 parts alcohol; bitter taste; 
neutral reaction. Citrated caffeine is more soluble, and much 
used in medicine. 

Theobromine, C 5 H 2 (CH 3 ) 2 N 4 2 . (Dimethyl xanthine.) 
Source: Seeds of Theobroma Cacao. 

Properties. White crystals ; slightly soluble in water, alco- 
hol and ether ; volatile at 290 ° ; neutral in reaction, but forms 
salts. 

PTOMAINES. 

Attention was first directed to the character of the poisonous 
principles contained in putrefying organic matter by the Italian, 
Selmi, in 1876. He extracted the putrefying substances \ ith 
alcohol, ether and chloroform, and thus obtained basic poison- 
ous compounds. These he called ptomaines, or cadaveric alka- 
loids. 

Ptomaines are feebly basic substances, containing nitrogen, 
formed by the action of bacteria upon nitrogenous organic mat- 
ter. They have been termed animal alkaloids, but since they 
are formed from vegetable as well as animal substances, this 
term is not at all appropriate, and should be used for the class 
of bodies known as leucomaines. 

The Formation of Ptomaines takes place as a result of the 



358 TEXT-BOOK OF CHEMISTRY 

putrefaction of nitrogenous organic matter, under the influence 
of moisture, suitable temperature, and presence of bacteria. 
The character of the ptomaine formed depends upon the kind 
of bacteria present, the nature of the substance decomposing, 
and the stage to which the decomposition has reached. The 
ptomaines are evidently formed by a cleavage action of bac- 
teria upon nitrogenous material, and they represent intermediate 
stages of decomposition in the return of this variety of organic 
matter to simple inorganic forms. 

The Properties of Ptomaines are much like those of the 
alkaloids. Some of them are liquid and volatile, others are 
solid non-volatile ; they are basic in reaction and form crystal- 
lizable salts with acids ; they are precipitated by the usual 
alkaloidal reagents. Ptomaines differ from alkaloids in being 
more easily decomposed, and for this reason they are more diffi- 
cult to prepare in a pure state. 

On account of this similarity in the properties of alkaloids 
and ptomaines, the toxicologist must be constantly on his guard 
in searching for poisons in putrefying bodies. Ptomaines have 
been found whose properties are almost duplicates of the alka- 
loids, atropine, conine, morphine, nicotine, strychnine, digitalin, 
colchicine, delphinine and veratrine. Vegetable alkaloids are 
sai-l to be separable from ptomaines by precipitating from 
ethereal soh tion with oxalic acid. This is done by adding a 
saturated solution of oxalic acid in ether, to an equal volume 
of the ethereal solution of the alkaloids, and allowing to stand ; 
the oxalates of the vegetable alkaloids will precipitate, leaving 
the ptomaines in solution. Cadaverine is said to be precipitated 
with the vegetable alkaloids. The reducing action of ptomaines 
upon potassium ferricyanide is made use of to distinguish them 
from alkaloids. If a drop or two of solution of a ptomaine be 
added to a solution containing ferric chloride and potassium 
ferricyanide, the ferricyanide is reduced to ferrocyanide and 



PTOMAINES 



359 



a deep blue precipitate of prussian blue is formed. The cir- 
cumstances attending the poisoning, and the symptoms of the 
patient, often furnish valuable aids in determining the charac- 
ter of the poison. 

Physiological Properties of Ptomaines. A large number 
are found to be not poisonous, and among these may be men- 
tioned, methylamine, di-methylamine , tri-methylamine , ethyl- 
amine, di-ethylamine, tri- ethyl amine and popylamine. 

Other ptomaines act as violent poisons, and the term toxine 
has been affixed to the names of such, to indicate this property. 
But the term toxine is now applied to those bacterial poisons 
which by absorption produce the symptoms of infectious disease. 

While a number of ptomaines are violent poisons, it is now 
quite certain that these bodies, representing, as they do, the 
cleavage action of bacteria on nitrogenous matter, are not the 
specific factors in the causation of disease. The specific bac- 
terial poisons are not ptomaines, but are synthetic products of 
bacterial life, and are properly called toxines. 

Very little is known at present in regard to the action of the 
individual ptomaines on the human system. Those cases of 
poisoning arising from the ingestion of decomposing food, 
formerly known as " ptomaine poisoning," may be in part due 
tx> the presence of ptomaines, but they are now regarded as 
being chiefly caused by toxines, and we speak, of " food poison- 
ing," or " toxine poisoning," instead of " ptomaine poisoning." 
In all probability, ptomaines and toxines are synergistic in their 
action, and both contribute in producing the symptoms ob- 
served. 

The symptoms produced by the ingestion of poisonous mush- 
rooms will probably furnish a fair illustration of the action of 
some of the ptomaines. These symptoms have their onset in 
from one-half to fifteen hours. There is giddiness, nausea, 
salivation, vomiting, abdominal pain, dimness of vision and 



360 TEXT-BOOK OF CHEMISTRY 

dyspnoea. A period of excitement is followed by drowsiness and 
convulsions. The heart's action is weakened ; the pulse is slow 
and small ; the pupils are at first contracted and finally dilated. 
Death occurs in coma or convulsions. The antidote is atropine, 
which counteracts the effect of muscarine upon the heart and 
respiration. 

Some of the poisonous ptomaines of interest are : 

Tyrotoxicon. Obtained from decomposing cheese, ice 
cream, milk and milk products. Discovered by Professor 
Vaughan in 1884. It acts as a violent poison. 

Muscarine. Found in poisonous mushrooms (Agaricus 
muscarius), has been made by artificial means and has been 
obtained from putrid fish. Acts as a violent poison, depressing 
the muscular tissue of the heart; action combated by atropine. 

Neurine has an action similar to that of curare. It is 
found in decomposing animal tissues, especially putrid fish. 

Typhotoxine is produced by cultures of the Eberth bacillus 
of typhoid fever when grown on beef-hash. This is not the 
specific poison of typhoid fever ; the nature of the soil has much 
to do with the formation of this ptomaine. 

Tetanine has been obtained from cultures of the tetanus 
germ, in an atmosphere of hydrogen, on beef broth. This 
ptomaine produces some, but by no means all, of the symptoms 
of tetanus. 

Cadaverine. Found in decomposing animal bodies, espe- 
cially fish. Acts as a powerful poison. 

LEUCOMAINES. 

The name, leucomaine, is derived from a Greek word sig- 
nifying white. It was applied by Gautier, who was the first 
to make a systematic study of these bodies. 

Leucomaines are nitrogenous basic substances, formed as 
products of tissue metabolism in the living body. They are 



LEUCOMAINES "361 



often called animal alkaloids, since they are usually the products 
of animal life. 

The sources from which leucomaines are derived are the 
nucleins of the nuclei, and the proteids of the protoplasm of 
cells. They are formed during- metabolism, in the tissues and 
cells of the body, probably by the action of enzymes or hydro- 
lytic agents, just as ptomaines are formed by the action of bac- 
teria upon dead proteids. 

The leucomaines are not active poisons, but their retention 
in the animal system results injuriously, producing headache, 
drowsiness, dullness and a general feeling of malaise. Inter- 
ference with the supply of oygen, or with the activity of the 
organs of elimination, results in the accumulation of leuco- 
maines in the tissues, a condition often referred to as auto- 
intoxication. 

Leucomaines are prepared from the various tissues of the 
body and from the excretions. The names of some of the more 
important ones are as follows : 

Uric Acid Group of Leucomaines: Purin, Adenin, Hypo- 
xanthine, Guanine, Methyl Guanine, Xanthine (Uric Acid). 1 

Creatinine Group of Leucomaines: Creatinine, Creatine, 
Crusocreatinine, Xanthocreatinine, &c. 

The Poisonous Proteids, or Toxalbumins. To this class be- 
long a number of bodies, proteid in character, represented by 
the venom of serpents ; extractives of bacteria ; and certain 
vegetable bodies, such as have been obtained from castor beans, 
and jequirity. 

On account of the ease with which they decompose and their 
resemblance to other albumens, the toxalbumins are extremely 
difficult to separate, and, for this reason, very little is known 
in regard to their chemical character. They are among the 
most poisonous bodies known and are much like bacterial 
toxins. 

1 An oxidation product of members of this group. 



362 TEXT-BOOK OF CHEMISTRY 

Of bacterial proteids, that of diphtheria, of tetanus, and of 
cholera, have been obtained from cultures of bacteria of these 
diseases. 

Very few vegetable poisonous proteids are known. Of ani- 
mal proteids, we have representatives in the poison of ser- 
pents, the serum of the Conger eel, and the poison of certain 
insects, such as spiders, &c. 

The venom of serpents, according to recent analyses, con- 
tains globulins and peptones, all of which are poisonous. This 
substance is an example of the most virulent of animal poisons. 

TOXINES AND ANTITOXINES. 

Soon after the discovery that the specific pathogenic bacteria 
are capable of producing basic poisonous bodies, or ptomaines, 
in animal bodies and in culture media, it was assumed that the 
symptoms of the infectious diseases were due to the presence 
of these bases. This view was soon abandoned, however, for 
it was found that filtered cultures are far more poisonous than 
the pure ptomaines themselves ; and that after the removal of 
basic constituents, the filtered cultures retain their excessive 
poisonous properties. 

These excessively poisonous bodies, which produce the 
symptoms of the infectious diseases, and which are formed 
by the action of bacteria in cultures and in the tissues of ani- 
mals, are called toxines. 

The chemical nature of toxines has not yet been determined, 
but they are known to be not basic, and there is not sufficient 
evidence to class them as ferments or albumens. 

A tetanus toxine has been obtained from cultures of the 
tetanus germ. This toxine, when purified, proved fatal to mice 
in doses of .000,000,05 gm. Analysis of such a toxine by 
Breiger showed the following composition : Carbon, 52.8 per 
cent. ; hydrogen, 8.1 per cent. ; nitrogen, 15.7 per cent. 



PROTEIDS 363 

Further experiments indicate that toxines are not the cleav- 
age products of bacterial action upon proteids, but that they 
are synthetic bodies formed as a result of bacterial life. These 
conclusions are justified by the fact that bacteria may be grown 
in culture media containing no proteids, and yet develop the 
poisonous toxines. This has been accomplished with the bac- 
teria of tetanus, diphtheria, typhoid fever and some others. 
The toxines formed in such cases have all the virulence pos- 
sessed by those grown in beef-broth. 

Antitoxines are bodies formed in the animal system in re- 
sponse to the stimulus afforded by toxines. They serve to com- 
bat the poisonous properties of toxines, and to confer an 
immunity which protects the animal from further invasion by 
the same disease. The toxine of each infectious disease, when 
inoculated into the animal system, produces its own specific 
antitoxine. 

The chemical composition and character of antitoxines is 
unknown. They are prepared for use in the treatment of 
disease, by injecting filtered cultures of bacteria, containing 
toxines, into an animal, in quantity insufficient to kill. These 
toxines stimulate the formation of antitoxine in the animal's 
blood. The blood of the inoculated animal is drawn off, and 
the sterile serum is used for treating the same disease by 
injecting into the human subject. 

In this way, antitoxines for treating various diseases have 
been prepared and are being used with success. The success 
that has attended the treatment of diphtheria with antitoxic 
serum has been sufficient to repay, many times, all the pains 
of investigators along this line. 

PROTEIDS. 

Occurrence in Nature. The members of this important 
class of organic bodies form the chief part of the solid and fluid 



364 TEXT-BOOK OF CHEMISTRY 

constituents of the body, and are found in all the organs and 
tissues. They are the chief substances in which physiological 
changes take place, and constitute the physical basis of life. 

Proteids cannot be formed by artificial means, nor are they 
produced within the animal body. The ultimate source from 
which they are all obtained is the vegetable kingdom. They 
are formed in the tissues of plants, from inorganic materials, 
under the influence of sunlight. 

Composition. Nothing definite is known in regard to their 
molecular structure, but they all contain carbon, hydrog'en, 
nitrogen and oxygen, and many contain sulphur and phos- 
phorus in addition. They contain some calcium phosphate and 
chlorides of the alkalies, which form the ash when they are 
burned. 

Analyses of the different proteids show the presence of the 
elements named in proportions which fall within the limits given 
in the following percentage formula : 

Carbon, 50.0 to 55.0 per cent 

Hydrogen, 6.6 to 7.3 per cent. 

Nitrogen, 15.0 to 19.0 per cent. 

Oxygen, 19.0 to 24.0 per cent. 

Sulphur, 0.3 to 2.4 per cent. 

The empirical formula is represented thus : 

C204H322N52O66S2. 

General Properties. The proteids are colorless, odorless, 
amorphous, nearly tasteless bodies. The peptones only are 
capable of dialysis. 

All are insoluble in alcohol ; some are soluble in water, others 
are insoluble. Some are soluble in weak saline solution, others 
are soluble in concentrated saline solution. All are soluble with 
the aid of heat in strong mineral acids, acetic acid and caustic 
alkalies. 

The conversion of soluble proteids into an insoluble form is 



PROTEIDS 365 

known as coagulation, and may be accomplished by heat (6o° 
or 70 ), by the action of some metallic salts, or by action of 
mineral acids. Coagulation is a permanent chemical change 
in the proteid molecule. 

The proteids form peptones by the action of gastric juice. 
They are not volatile, and they easily undergo decomposition by 
putrefaction. They all turn the ray of polarized light to the 
left. 

Action of Heat upon Proteids. When heated with ex- 
clusion of air they form Dippel's oil, which contains ammonium 
salts of fatty acids, various amines of the fatty and aromatic 
hydrocarbons, and phenol, pyridine and quinoline bases. 

Action of Acids and Alkalies. Boiling with strong hydro- 
chloric or sulphuric acid produces nearly the same changes as 
heating with caustic alkalies. The bodies formed are chiefly 
ammonia, fatty acids, amido-acids, leucin, tyrosin, indol and 
skatol. 

Strong Oxidizing Agents produce aldehydes, cyanides and 
fatty and aromatic acids. Nitric acid produces xanthoproteic 
acid, and finally, oxybenzoic acid. Chlorine forms, amongst 
other products, oxalic acid. 

The action of putrefactive ferments is first that of peptoniza- 
tion (or liquefaction), and then the formation of a number of 
amines, amides, fatty and aromatic acids. Ammonia and 
hydrogen sulphide are also formed. 

In the digestion of proteids, the action, in general, is to 
change them into proteoses and peptones, under the influence 
of the various digestive ferments. 

General Reactions of Proteids. 

Use an aqueous solution of Qgg albumin, 1 in 50. 

1. Heated with strong nitric acid, they turn yellow, and the 
color deepens to orange on adding the hydroxide of ammonium, 
potassium or sodium. 



366 TEXT-BOOK OF CHEMISTRY 

2. Milloris Reagent added to the proteid gives a white pre- 
cipitate which turns brick-red on heating. Millon's reagent is 
made by dissolving one part mercury in two parts strong nitric 
acid by the aid of gentle heat. The resulting solution is diluted 
with twice its volume of water, and the precipitate allowed to 
settle. The clear supernatant liquid is used as the reagent. 

3. Lieberman's Reaction. When albumin is precipitated 
with alcohol and washed with ether and dried, it gives a deep- 
violet color when heated with hydrochloric acid. 

4. To precipitate all proteids except peptones, add acetic acid 
to distinct acid reaction, and then a strong solution of sodium 
sulphate, and boil. This test is useful to separate albumin 
from solutions before testing for sugar. 

5. To precipitate all proteids : Add tannic acid, to solutions 
acidulated with acetic acid; or add double iodide of mercury 
and potassium, with slight excess of hydrochloric acid. 

6. All proteids except peptones are precipitated by ammo- 
nium sulphate solution. 

7. Biuret Reaction. Add a few drops of dilute solution of 
cupric sulphate, and then an excess of solution of caustic 
potash ; a violet color makes its appearance. 

CLASSIFICATION OF PROTEIDS. 

There are many systems of classification of proteids in use 
by different authors. It is greatly to be desired that some uni- 
form plan shall be adopted. The following arrangement is 
Gray's modification of Hall's classification : it is both simple and 
comprehensive : 

A. Simple Proteids: 

I. Albumins. II. Globulins. 

a. Egg albumin, a. Serum globulin, 

b. Serum albumin, b. Fibrinogen, 

c. Lacto-albumin, c. Myosinogen, 

d. Myo-albumin, d. Myo-globulin, 

e. Vegetable albumin. e. Globin. 

f. Crystallin, 

g. Vegetable globulin. 



PROTEIDS 



.367 



II. Chromo proteids. 

a. Hemoglobin, 

b. Histo-hematin. 



II. Proteoses and Peptones. 



II. Derived albuminoids. 
a. Gelatin. 



B. Combined Proteids : 

I. Nucleo proteids. 

a. Caseinogen, 

b. Vitellin, 

c. Nuclein. 

C. Derived Proteids: 

I. Albuminates. 

a. Acid albumin, 

b. Alkali albumin. 

D. Albumenoids: 

I. Native albuminoids. 

a. Collagen, 

b. Elastin, 

c. Mucin, 

d. Keratin. 

Simple Proteids. 

Albumins are soluble in water and in saturated solution of 
magnesium sulphate or sodium chloride, but insoluble in satur- 
ated solution of ammonium sulphate. They are coagulated by 
moderate heat, 63 ° to 75 ° C, and by acids and alcohol. Native 
albumins are : 1. Egg albumin, which is precipitated by ether. 
2. Serum albumin, not precipitated by ether. This is the prin- 
cipal proteid constituent of the blood plasma. 3. Lacto-albu- 
min, from milk. It is seen at the surface as scum when milk 
is boiled. 4. Myo-albumin, one of the proteids from muscle 
tissue. 5. Vegetable albumin, found in plants. 

Globulins are insoluble in water and saturated salt solution, 
but soluble in dilute solution of sodium chloride. The presence 
of a small quantity of sodium chloride in the blood keeps them 
in solution. They are: 1. Serum globulin, or paraglobulin, a. 
proteid of the blood plasma, and of chyle and lymph. 2. Fib- 
rinogen, another proteid of the blood plasma, which differs 
from the foregoing in being coagulated by the fibrin ferment 
and calcium salts, the coagulated fibrinogen being called fibrin. 
It also coagulates at a lower temperature than serum albumin, 
and is as completely precipitated by sodium chloride as by 



368 TEXT-BOOK OF CHEMISTRY 

magnesium sulphate. 3. Myosinogen exists in living muscle. 
It coagulates after death to form myosin. 4. Myo-globulin is 
associated with myosinogen in muscle tissue. 5. Globin is 
found in the hemoglobin of the blood. 6. Crystallin is found 
in the crystalline lens of the eye. 

Combined Proteids. 

Nucleo Proteids are compounds of nuclein with proteids. 
Nuclein contains phosphorus, and hence all nucleo proteids con- 
tain this element. They generally also contain iron. They are : 
1. Casein, or more properly caseinogen, the principal proteid 
of milk. 2. Vitellin, the chief proteid of the yolk of the egg. 
3. Nuclein, or cell nuclein, the chief proteid of the nuclei of 
animal as well as of vegetable cells. Casein and vitellin are 
peculiar to certain animals. 

Chromo Proteids are compounds of a proteid with an animal 
coloring matter. They are: 1. Hemoglobin, containing globin 
and hematin. The pigment, hematin, contains iron. 2. Histo- 
hematin, or tissue hematin, found especially in muscle. 

Derived Proteids, or derived albumins. To this class are 
referred all proteids derived from native or combined proteids 
developed by physiological processes. 

Albuminates are derived from native proteids by action of 
dilute acid or alkali. They are: 1. Acid albumin, formed in 
the stomach by the action of hydrochloric acid or other acid. 
Syntonin is a corresponding derivative of myosin. 2. Alkali 
albumin, formed by action of pancreatic juice on native 
proteids. 

Proteoses and Peptones are derived from proteids or albu- 
minates by hydrolysis by the process of digestion. 

Albuminoids are closely related chemically to the other 
proteids, and are derived by processes of metabolism. 

Native Albuminoids. Those existing normally are: I. 



PROTEIDS . 369 

Collagen, composing white fibrous tissue, also found in car- 
tilage and in bone. 2. Elastin, composing yellow elastic tissue. 
3. Mucin, the chief constituent of mucus, and found also in 
gastric juice. It has been classed as a glyco-proteid from being 
combined with a carbohydrate. 4. Keratin, the horny material 
of the nails, hair, skin, &c. Neurokeratin is found in the 
medullary sheath of nerves. 

Derived Albuminoids. Of these, only one need be men- 
tioned, Gelatin. It is obtained from collagen by hydration, 
which is accomplished by boiling with water. 



25 



PART V. 



THE METHODS OF QUANTITATIVE ANALYSIS. 

Qualitative analysis is analysis having for its object the de- 
termination of the character of bodies. Quantitative analysis 
determines the quantity of a substance. 

Solution of the substance is usually the first step in analysis. 
If the substance be insoluble in water it may sometimes be dis- 
solved in acidified water, or it may be rendered soluble by treat- 
ment with hydrochloric, nitric, or nitro-hydrochloric acids. 
When a substance has been dissolved in a strong acid for 
analysis, the liquid should be evaporated nearly to dryness, to 
remove excess of acid, and the residue dissolved in distilled 
water. Those bodies which cannot be made to dissolve by the 
aid of acids,- as described, must be fused with a mixture of 
potassium and sodium carbonates. The resulting mass is then 
dissolved in distilled water. 

The methods of quantitative analysis are usually of two 
kinds, viz. : Gravimetric and Volumetric. 

The Gravimetric Method. 
The gravimetric method of analysis consists, essentially, in 
the precipitation of the substance ; the separation, drying, and 
weighing of the precipitate; the calculation of the quantity of 
substance from weight of precipitate. 

Precipitation of the substance is accomplished by adding to 
the solution, in a beaker, test-tube, or other convenient vessel, 
the precipitating agent. The precipitating agent usually con- 

37i 



372 



TEXT-BOOK OF CHEMISTRY 



sists of a body in solution which will form an insoluble definite 
compound with the substance which precipitates. Care should 
be taken to see that all the substance is thrown out of solution 
by the precipitant, a few drops of the latter being added after 
each subsidence of the precipitate until no further reaction 
occurs. Heating the liquid facilitates the chemical changes 
resulting in precipitation ; it also causes an agglutination of the 
fine particles of some precipitates, thus facilitating their separa- 
tion from the liquid by filtration. 

The precipitate may be separated by decantation or filtration. 
Decantation consists in pouring off the supernatant liquid from 



Fig. 40. 



a precipitate which has settled. 
More complete separation may be 
accomplished here by allowing the 
precipitate to drain. 

Filtration, Filters are made of 
various kinds of material, but they 
usually consist of porous paper, 
purified by washing with dilute 
hydrochloric acid. The filter is 
properly folded, placed in a funnel, 
and the mixture of liquid and pre- 
cipitate poured in. By this means, 
two portions are obtained, viz : a 
filtrate, the portion running 
through; and a precipitate, that 
remaining on the filter. In order 

to obtain the precipitate in a pure state, it should be well 

washed with distilled water. 

The precipitate, to be dried, may be placed with the funnel 

in a drying oven, and the temperature kept at ioo° to 105 

for a sufficient length of time to completely remove moisture. 
Many precipitates require to be ignited in order to convert 




Drying Oven. (After 
Coblentz.) 



METHODS OF QUANTITATIVE ANALYSIS 



373 



them into compounds of definite composition. This is done by 
detaching the dried precipitate and placing it in a suitable 
crucible, and heating. The filter paper, containing some un- 
detachable particles of precipitate, is burned upon the crucible 
lid, and its ash added to the crucible contents. The crucible 
and contents are then cooled over sulphuric acid in a desiccator. 

Fig. 41. 




Desiccator. 



The weight of the precipitate is determined by weighing 
crucible and contents, and deducting the weight of crucible and 
filter ash ; or the precipitate may be carefully removed to a 
watch glass and weighed. 

The next step in analysis is to calculate the quantity of sub- 
stance from the weight of precipitate. Suppose, in the above 
described series of experiments, we had desired to find the 
quantity of sulphuric acid in the original solution, and had 
obtained a precipitate of barium sulphate by adding barium 
chloride to the solution. In such a case, it would be an easy 
matter to calculate the quantity of sulphuric acid represented 
by a given quantity of BaS0 4 , by reference to the methods of 
chemical calculation on page 74. Each gram of barium sul- 
phate represents 98/233 gram of sulphuric acid. 



374 TEXT-BOOK OF CHEMISTRY 

The Volumetric Method. 

The volumetric method of analysis is performed by measur- 
ing, as the name implies. It consists, essentially, in adding 
just enough of the reagent, to the substance tested, to produce 
a definite chemical reaction ; and then calculating the quantity 
of substance from the quantity of reagent used. 

The reagent for volumetric analysis is made by dissolving 
its molecular weight in grams (gram molecule) in one liter 
of distilled water at 15 C, for univalent compounds; one 
half this quantity for bivalent compounds ; one third this quan- 
tity for trivalent compounds, &c. Such solutions are known 
as normal solutions, expressed thus, ^. Deci-normal, ~ [ f 
and Centi-normal, y^, solutions are often employed. 

Normal solutions contain the hydrogen equivalent of the 
active reagent in grams per liter — Deci- and Centi-normal solu- 
tions contain the tenth or hundredth of the same equivalent. 
The molecular weight of caustic soda (NaOH) is 39.96; there- 
fore the normal test solution of caustic soda is made by dis- 
solving 39.96 gm. of this compound in water sufficient to make 
one liter (1000 cc). The molecular weight of pure crystal- 
lized oxalic acid is 127.5, corresponding to the formula, 
H 2 C 2 4 .2H 2 0. But this compound is bivalent, containing two 
replaceable hydrogen atoms, and the normal test solution is 
made by taking one-half the molecular weight in grams, 62.85 
gm., and dissolving in water to make one liter. 

Each of the two solutions described is equivalent to the 
other — 1 cc. of one being exactly neutralized by 1 cc. of the 
other. In the same way, all normal solutions are equivalent. 

Standard Solutions are those which contain a known definite 
amount of reagent to be used in volumetric analysis. Such a 
solution may or may not be normal. Fehling's solution, the 
formula for which has already been given, is an example of 
a standard solution. It is made of such strength that 1 cc. is 
the equivalent of .005 gm. glucose. 



METHODS OF QUANTITATIVE ANALYSIS 



375 



Fig. 42. 



In testing a substance by means of a volumetric solution, 
the substance is placed in a beaker, or suitable vessel, and 
the reagent is added, drop by 
drop, from a graduated burette, 
until the chemical change it pro- 
duces is just completed. Comple- 
tion of the chemical change is in- 
dicated by a change in the appear- 
ance of the mixed liquids, or by a 
change in color or appearance of 
some substance which has been 
added, and which is called an indi- 
cator. Phenol-phthalein is one of 
the bodies used as an indicator. 
This substance is colorless in acid 
or neutral media, but develops a 
beautiful purple-violet color when 
the medium becomes alkaline. If 
a few drops of phenol-phthalein 
in alcohol, be added to a solution of 
oxalic acid, and then caustic soda 
be added, drop by drop, the mo- 
ment all acid is neutralized and the 
liquid becomes alkaline, it assumes 
a purple-violet color. By the use 
of this indicator, it is possible to 
tell the moment acids or alkalies 
are neutralized — one by the other. 
Various other indicators are em- 
ployed, among which are — litmus, 
rosolic acid, methyl orange, starch 
mucilage, &c. 




Titration. 



376 TEXT-BOOK OF CHEMISTRY 

Titration is the operation of applying the volumetric test, 
as described above. The expression, titer, is sometimes em- 
ployed in the sense of standard, meaning the strength per liter 
or cc. of the test solution. 

The methods of titration are usually of three kinds, viz. : 
Direct, Indirect, and Residual. 

In the Direct Method the solution to be tested is acted upon 
by the reagent by simple contact with an equivalent quantity, as 
by the neutralization of an acid by a base, or vice versa. 

The Indirect Method consists in the formation of a sub- 
stance which liberates an equivalent quantity of another body, 
and by determining the quantity of the second body, the quan- 
tity of the first may be estimated. An example of this is found 
in testing for oxygen by heating the substance with hydro- 
chloric acid and liberating chlorine. By determining the quan- 
tity of chlorine with potassium iodide and sodium hyposulphite, 
the equivalent quantity of oxygen may be estimated. 

The Residual Method consists in adding a known quantity 
of reagent, in excess, determining the quantity which remains 
undecomposed, and the difference between the two represents 
the equivalent quantity of reagent which was consumed in the 
reaction. An example of this method is afforded in testing 
a sample of calcium carbonate, CaCO s . Since it is not possible 
to add with any degree of accuracy the precise quantity of acid 
required for its neutralization, an excess of acid is added. The 
acid liquid is then titrated with normal alkali, by which means 
the quantity of undecomposed acid is determined, and this, 
deducted from the total quantity used, gives the amount which 
was consumed in neutralizing the calcium carbonate. 

Calculation of Results. 
In order to calculate the quantity of substance from the 
quantity of reagent used, reference is made to the atomic and 



METHODS OF QUANTITATIVE ANALYSIS 377 

molecular weights of the bodies entering into the reaction. 
For example, if we desire to determine the quantity of hydro- 
chloric acid in a given quantity, say 10 cc, of solution of this 
acid by titration with normal potassium hydroxide solution, the 
following equation gives the basis for the calculation, thus : 

HC1 + KOH = KC1 + HoO, 
36.4 + 56 = 74.4 + 18. 

Remembering that normal KOH solution contains the gram 
molecule (56 gm.) per 1000 cc, this equation shows that I 
cc. normal KOH solution requires .0364 gm. hydrochloric acid 
for its neutralization. 

Suppose, in neutralizing the above 10 cc. of solution of HC1, 
30 cc. of normal KOH solution were required. 1 cc. normal 
KOH requires .0364 gm. HC1 for its neutralization, therefore 
the 10 cc. acid solution contains, 

•0364 X 30 = 1.0920 gm. HC1. 

100 cc. of the liquid would contain ten times this quantity, 
or 10.92 gm., or 10.92 per cent. 

This example serves as an illustration of the principles in- 
volved in calculating the results of the volumetric analysis. 

The following table shows more accurately a number of 
neutralization equivalents in grams. 

One cc. Normal Acid is Equivalent to One cc. of Normal Alkali is Equivalent to 

Ammonia 0.01701 Acetic acid . . : 0.05986 

Ammonium carbonate . . . 0.05226 Citric acid 0.06983 

Lead subacetate 0.13662 Hydrobromic acid 0.08076 

Lithium carbonate 0.03693 Hydrochloric acid 0.03637 

Potassium bicarbonate . . . 0.09988 Hydriodic acid 0.12753 



Potassium carbonate .... 0.06895 Lactic acid 0.0c 

Potassium hydroxide 0.05599 Nitric acid 0.06289 

Sodium bicarbonate 0.08385 Oxalic acid 0.06285 

Sodium carbonate 0.05292 Sulphuric acid 0.04891 

Sodium hydroxide 0.03996 Tartaric acid 0.07482 

For the further study of quantitative methods the student is 
referred to works on chemical analvsis. 



PART VI. 



PHYSIOLOGICAL CHEMISTRY. 

INTRODUCTION. 

Most of the vital activities of plants and animals are de- 
pendent upon the operation of chemical and physical, or me- 
chanical, laws but these laws have not been sufficient, as yet, 
to explain all of the phenomena to be observed in the living 
cell. 

Neither physics nor chemistry has ever been able to explain 
why it is that the cells of certain secretory glands, such as the 
mammary, are capable of removing from the blood the exact 
proportions of organic and inorganic constituents found in milk ; 
or by what process the secretory cells of the glands of the 
stomach are capable of forming hydrochloric acid from sodium 
chloride, in the immediate proximity to sodium carbonate of 
the blood. 

Certain unicellular forms of life, such as the Vampyrella 
Spirogyra, display a selective action in seeking their food 
which amounts almost to that of a conscious being. This 
minute mass of protoplasm will refuse various forms of sub- 
stance until it comes to certain species of algae, the Spirogyra, 
and, attaching itself to the cellular envelope, will dissolve this 
and absorb its contents. 

Finding a specific intentional activity in this simple cell, it is 
equally possible that the various cells of the animal body are ca- 
pable of similar conduct. We speak of the passage of nutritious 
material through the intestinal walls by a process of osmosis: 

379 



3^0 TEXT-BOOK OF CHEMISTRY 

but the intestinal wall does not act like a dead membrane; it 
is lined with living cells, which by their selective action, allow 
certain substances to pass through into the circulation, denying 
entrance to others. It has been shown that the intestinal cells 
of cold blooded animals during the absorption of fat, send out 
processes to envelope the fat globule, which is then incorporated 
into its substance, and afterwards allowed to pass through into 
the lacteals. 

The abandonment of the theory of " vital force " in the 
sense that it affects the character of the products or compounds 
formed by a living organism is eminently correct, but we should 
take pains not to apply these ideas to the activities of living 
protoplasm. 

RELATION BETWEEN PLANT AND ANIMAL LIFE. 

Physiological chemistry is the chemistry of living organisms. 
It embraces a study of the chemical changes taking place in the 
plant and animal, and the relation of these changes to vital 
phenomena. 

The physical and chemical changes taking place in a healthy 
plant or animal are known as normal changes ; those occurring 
in a diseased plant or animal are known as abnormal, or 
pathological. A study of the chemical changes and their prod- 
ucts in a diseased plant or animal, is known as pathological 
chemistry. 

Plants, under the influence of sunlight, absorb inorganic 
substances and build up complex unstable molecules, in which 
great quantities of energy are stored. These molecules furnish 
sources of food and energy for the animal, in whose tissues 
they are disintegrated and returned to inorganic forms. 

The tissues of plants are made up chiefly of the elements 
carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, 



PHYSIOLOGICAL CHEMISTRY .38 I 

silicon and the metals iron, calcium, potassium, sodium and 
magnesium. The substances serving as plant food are taken 
up chiefly by the roots, which throw out an acid secretion, thus 
increasing the solubility of the materials with which they come 
in contact. The roots absorb" water, carbon dioxide, nitrates, 
nitrites, ammonia, and the salts of the metals, besides more 
or less of silicon. The green parts of the plant contain 
chlorophyl, which under the influence of sunlight serves the 
function of eliminating such oxygen as is not needed, and of 
absorbing carbon dioxide from the air ; this action, which takes 
place in the leaves and bark of the plant, is known as plant 
respiration. 

The plant, in securing a supply of the elements named, ob- 
tains its carbon from carbon dioxide, its hydrogen from water, 
and such oxygen as is needed, from these sources also. 

It obtains nitrogen from ammonia, nitrates and nitrites ; sul- 
phur from sulphates ; phosphorus from phosphates ; and the 
elements calcium, magnesium, potassium, sodium, iron and 
silicon from salts of these metals in the soil. 

The animal receives the chief portion of its food from plant 
sources, either directly, or indirectly through the flesh of other 
animals. On the other hand, the excrementitious products of 
animal life furnish material for plant nutrition. Animals ex- 
crete carbon dioxide, water, urea, urates ; phosphates, sulphates, 
and chlorides of calcium, sodium, magnesium, and potassium, 
while plants utilize these same products for food. The animal 
utilizes the oxygen given off in plant respiration, while the plant 
utilizes the carbon dioxide given off during animal respiration. 

Thus, it is clear that a mutual adjustment between the mem- 
bers of the vegetable and animal kingdoms exists ; the activities 
of plant life serving to build up food containing energy, for 
the animal, and the animal furnishing simple, inorganic, ex- 
crementitious material which serves as food for the plant. 



3 8 2 TEXT-BOOK OF CHEMISTRY 

CHEMICAL COMPOSITION OF THE HUMAN BODY. 

Only a comparatively small number of all the elements known 
enter into the formation of the human body. The chief of these 
have been mentioned in considering the elements. The elements 
and the proportions in which they occur in the body are as 
follows : 

Carbon, 13.50 per cent. ; Hydrogen, 9.10 per cent. ; 

Oxygen, 7.2 per cent. ; Nitrogen, 2.5 per cent. ; Phosphorus, 
1. 15 per cent. ; 

Calcium, 1.30 per cent.; Sulphur, 0.147 per cent; 

Sodium, 0.10 per cent. ; Potassium, .026 per cent. ; 

Chlorine, 0.085 P er cent - 5 an d the elements fluorine, iron, 
silicon, and magnesium in small and varying quantities. 

A mere statement of the percentage of the different elements 
found in the body gives little idea of the real chemical composi- 
tion of the different tissues and fluids. These elements are 
found in many different forms of combination, forming liquid 
and solid compounds, both organic and inorganic. By proxi- 
mate analysis, these compounds have been more or less per- 
fectly separated into what have been called proximate princi- 
ples, most of which have been described under the section on 
descriptive chemistry. 

The important organic compounds occurring in the human 
body are found as members of the following groups, viz., Car- 
bohydrates, Fats and Proteids, all of which have been fully 
described. The inorganic constituents found are as follows, 
viz., water; calcium phosphate, Ca 3 (P0 4 ) 2 ; calcium carbonate, 
CaC0 3 ; calcium fluoride, CaF 2 ; sodium chloride, NaCl ; 
sodium phosphate, Na 2 HP0 4 ; sodium carbonate, Na 2 CO s ; 
sodium sulphate, Na 2 S0 4 ; potassium chloride, KC1 ; potassium 
phosphate, K 2 HP0 4 ; potassium carbonate, K 2 CO s ; magnesium 
phosphate, Mg 3 (P0 4 ) 2 ; magnesium carbonate, MgCO s ; iron, 
in hemoglobin of the blood and traces in other tissues and 
fluids. 



PHYSIOLOGICAL CHEMISTRY 383 

A number of other compounds are found, most of which 
probably represent different stages of tissue consumption or 
retrograde metamorphosis. They are: acetic, lactic, oxalic, 
butyric and propionic acids ; urea, uric acid, xanthin, hippuric 
acid, creatin, creatinin, &c. ; alcohol, glycerin, cholesterin ; and 
certain pigments, as those found in urine and bile. 

Animal Food. The energy manifested in the various activi- 
ties of the animal organism results in the disintegration or con- 
sumption of the living tissue cells. In consequence of this dis- 
integration, materials have to be constantly supplied for the 
restoration and maintenance of cellular integrity. Foods are 
substances which when taken into the animal body yield energy 
by their own disintegration, furnish constructive material to 
cells, or prevent cellular consumption. 

The substances used as foods contain compounds correspond- 
ing to those found in the body. These compounds are of four 
kinds, viz. : Proteids, carbohydrates, fats, and inorganic salts, 
including water. The compounds themselves are known as 
food principles, in contra-distinction to the crude articles of 
diet. 

The animal body is thus seen to be a kind of machine, capable 
of self-restoration and regulation within certain limits. It 
takes up compounds of complex molecular structure found in 
the crude articles of diet, and by their gradual oxidation and 
disintegration it utilizes the store of energy which they con- 
tain. This energy is manifested in heat, muscular activity, 
mental activity, and the various other forms of motion of which 
the body is capable. 

The value of a substance for food is measured by the amount 
of energy it is capable of producing. This is generally ex- 
pressed in heat units, or calories. The heat producing value of 
a given article of food is determined by means of the calorim- 
eter. Fats and carbohydrates produce the same amount of 



384 TEXT-BOOK OF CHEMISTRY 

heat when burned in the calorimeter as when consumed in the 
animal body. In the case of proteids, the quantity is greater, 
because proteids are only oxidized to the extent of urea in 
animals ; but the difference is known to be 2.523 calories, which 
is the number of heat units produced by burning urea. The 

Fig. 43. 




Calorimeter. 

number of kilogram calories, 1 when this difference is ac- 
counted for, is about the same for carbohydrates and proteids 
when consumed in the animal body. The heat value of the 
three important energy-producing foods in kilogram calories 
is shown to be as follows : 

1 gram proteid or carbohydrate yields 4.120 calories. 

1 gram fat yields 9-353 calories. 

x The kilogram calorie is the quantity of heat required to raise the 
temperature of 1 kilogram of water from o° to i° C. 



PHYSIOLOGICAL CHEMISTRY - 385 

The Utilization of Food. The proteids of the food, after 
undergoing digestion and conversion into peptones, pass into 
the blood stream in the form of proteids characteristic of the 
blood, and are carried to> the tissues where they enter, in part 
or entirely, into the structure of the protoplasm of tissue cells. 

In the process of metabolism, the proteids become oxidized 
and undergo disintegration. They are converted into a com- 
pound containing carbon, probably a carbohydrate, and into 
other compounds containing nitrogen. The nitrogenous end 
product of proteid metabolism is urea, and the probable ante- 
cedents to the formation of urea are creatin, glycocol, sarco- 
lactic acid, ammonium lactate, ammonium carbonate and am- 
monium carbamate. The disintegration of the proteid mole- 
cule is attended by the liberation of energy. 

The Fats after digestion pass into' the lymphatic vessels and 
through the thoracic duct into the circulation. They rapidly 
disappear from the circulation, and are believed to supply body 
fat in part, but the larger portion is directly oxidized into car- 
bon dioxide and water, setting free the large quantity of mo- 
lecular energy which they contain. The fat of the tissues is 
partly supplied in the disintegration of the proteid and car- 
bohydrate molecule. 

The Carbohydrates are converted into dextrose by digestion 
and pass into the circulation as such. A large portion is stored 
in the liver and muscles as glycogen ; a large portion is at once 
oxidized, liberating its molecular energy ; a portion contributes 
to the formation of fat. 

The inorganic food principles, though used in smaller amount 
than the organic, are equally necessary for the maintenance of 
physiological activities. 

Water is absorbed directly into the circulation after its 
ingestion. Its presence in all the fluids and tissues of the body 
is necessary in order that they may perform their functions. 
26 



3§6 TEXT-BOOK OF CHEMISTRY 

It serves to dissolve the food principles and to carry them in 
the blood and lymph stream to the body tissues. It serves to 
dissolve the waste products of metabolism, and to remove 
them, by its elimination through the various excretory glands. 

Sodium Chloride is taken into the body with the food, both 
as a constituent of the usual food-stuffs and as a condiment. 
By its presence it facilitates the solution of various body prin- 
ciples, it facilitates cellular activity, and it is believed to fur- 
nish the chief material from which hydrochloric acid of gastric 
juice is formed. 

Potassium Phosphate and Carbonate and the corresponding 
salts of sodium furnish a mild degree of alkalinity to the blood 
and lymph, a condition necessary to the activity of tissue cells. 

Of Calcium Salts, the phosphate and carbonate ' are utilized 
in the structure of bones and teeth, and the phosphate is found 
in the nervous tissues. The absence of the salts of calcium 
from the food of young animals produces a condition similar 
to that seen in rickets. 

Iron is taken into the animal from organic and inorganic 
sources, and it enters into the composition of the hemoglobin 
of the blood : it is also found in traces in other tissues, and it 
is eliminated chiefly by the feces. 

Vegetable Acids serve to increase the secretion of the diges- 
tive fluids, and, entering the circulation as salts, they increase 
elimination through the kidneys. Entire absence of vegetable 
acids from the diet results in the development of scurvy, while 
an excessive quantity gives flatulence and diarrhea. 

The Supplementary Foods, coffee, tea and cocoa, act as 
stimulants to the nervous system and heart, relieving the sense 
of fatigue following mental or physical exertion, and increas- 
ing the power of continuous mental effort, but they have no 
influence over proteid metabolism. These supplementary foods 
depend upon the presence of the alkaloids, caffeine, theine, and 



PHYSIOLOGICAL CHEMISTRY - 387 

theobromine for their stimulating and sustaining properties. 
Tea contains a large percentage of tannic acid which is liable 
to act as an irritant to the digestive organs when this beverage 
is taken in large amount. Cocoa has a certain nutritive value 
not possessed by the others on account of the fat and proteid 
which it contains. 

Alcohol, when taken in small amount, acts as a stimulant to 
the digestive organs. It increases the heart's action and dilates 
the arterioles, producing a sense of warmth, but it increases 
heat elimination. It produces excitation of the brain. In large 
quantities alcohol acts as a paralyzant, and deranges the organs 
of digestion. The long-continued use of alcohol, even in mod- 
erate amount, is liable to derange the digestive organs by its 
irritant action upon the mucous membrane, and give rise to 
digestive disturbances. In excessive quantities it produces 
muscular weakness, lessened mental power, depression of tem- 
perature, and structural changes in the liver, kidneys, brain, 
spinal cord and other organs of the body. - 

Alcohol is oxidized in the tissues, and thus temporarily con- 
tributes to bodily energy, but experimental evidence does not 
show conclusively that it has any value as an article of food. 
The relation of alcohol to proteid metabolism is still a matter 
of experimental investigation, however, and the question of its 
value as an article of food has not been satisfactorily deter- 
mined. 

The Blood is a highly complex fluid, and as found in the 
animal body it is of two kinds, viz., arterial, or oxidized blood, 
having a bright red color ; and venous, or deoxidized blood, 
whose color is of a darker hue. 

Blood is an opaque liquid ; it has a peculiar odor, which is 
augmented by the addition of sulphuric acid ; its reaction is 
alkaline, due to the presence of disodium phosphate and sodium 
carbonate; its specific gravity averages 1.056 in the male, and 



388 



TEXT-BOOK OF CHEMISTRY 



1.053 in the female. The temperature of the blood in health 
varies from 98.2 ° F., in the superior vena cava, to 103.4 F. in 
the hepatic vein. 

The microscope reveals the fact that blood is made up of a 
fluid portion, called plasma, and of certain minute solid bodies 
floating in the plasma, known as corpuscles. 

A few minutes after blood is drawn from the animal, about 
five to seven minutes in the human subject, it undergoes a 
change which results in its conversion into a semisolid, gela- 
tinous mass. This change is known as coagulation. A micro- 
scopic examination of coagulated blood shows the presence of 
a network of fine fibrils extending in all directions through its 
substance, having the corpuscles entangled in its meshes. 
These fibrils consist of fibrin. Fibrin may be obtained free 
from other substance by stirring the blood, as it coagulates, 
with a bundle of small glass rods to which the fibrin adheres, 
and then washing with pure water in order to remove the 
blood corpuscles. 

Fibrin is a form of proteid which is produced by coagula- 
tion of the fibrinogen of blood plasma under the influence of 

Fig. 44. 




o o5oq 

cul°s o oft 




Coagulating Blood. 



the fibrin ferment in the presence of calcium salts, when blood 
is drawn from the body. The exact chemical changes taking 
place in coagulation of the blood are not known at the present 
time. 



PHYSIOLOGICAL CHEMISTRY _ 389 

When coagulated blood is allowed to stand for a time a 
clear, straw colored fluid, called blood serum, makes its appear- 
ance on the surface of the clot. Upon further standing, the 
fibrin contracts into a smaller mass, with separation of serum, 
until finally it forms, with the enclosed corpuscles, a red clot 
which floats indifferently in the surrounding serum. 

If blood be prevented from coagulating by the addition of 
magnesium sulphate (i volume of a 25 per cent, solution to 
three volumes of blood), or by other suitable means, the cor- 
puscular portion settles to the bottom of the vessel, forming a 
layer somewhat less than one-half the total volume. The super- 
natant, or fluid portion, constitutes the plasma. 

Plasma is a transparent, pale yellow, slightly viscid liquid; 
having a specific gravity of 1.026 to 1.029. It is composed of 
water, proteids, sugar, fatty matter, urea, cholesterin, lecithin, 
and the inorganic salts, sodium chloride, potassium chloride, 
potassium sulphate, sodium phosphate, sodium carbonate, cal- 
cium phosphate and magnesium phosphate. 

The proteids of plasma are serum-albumen, paraglobulin 
and fibrinogen. The last named is converted into fibrin during 
coagulation. 

The Blood Corpuscles are of three kinds, viz., Erythrocytes, 
or red blood cells ; Leucocytes, or white blood cells ; Blood 
plaques, or blood plates. 

The Red Corpuscle is non-nucleated; its shape is that of a 
circular, flattened, biconcave disk; when viewed under the 
microscope it has a yellowish color; its transverse diameter is 
.0075 mm. ; its thickness is .0019 mm. ; it is a structureless 
mass of protoplasm, containing hemoglobin, which can be 
dissolved out with distilled water. Besides hemoglobin, the 
blood corpuscle contains a proteid, lecithin, cholesterin, potas- 
sium phosphate and other inorganic salts in minute amount. 



390 



TEXT-BOOK OF CHEMISTRY 



The Amount of Hemoglobin present in the blood corpuscle 
is estimated to be 90 per cent. ; this is in the amorphous con- 
dition and combined with the protoplasm of the cell. By treat- 
ing the corpuscles with distilled water and slowly evaporating, 

Fig. 45- 




Hemoglobin Crystals. (Brubaker.) a-b, human 
e, hamster ; f, squirrel. 



c, cat ; d, guinea pig : 



the hemoglobin may be obtained in the form of rhombic, 
prismatic crystals, of red color. Hemoglobin contains from 
.4 to .6 per cent, of iron ; it has a strong affinity for oxygen, 
which, however, it readily gives up to other bodies. Hemo- 
globin serves as the oxygen-carrying substance of the blood. 
Oxy-hemoglobin is the oxidized variety, found in arterial 



PHYSIOLOGICAL CHEMISTRY 39 I 

blood; reduced hemoglobin is found in venous blood. Meth- 
hemoglobin is a modified form of hemoglobin, found in certain 
fluids, such as cystic fluids, and blood transudates. 

The chemical analysis of hemoglobin freed from water of 
crystallization by drying at ioo°, shows a probable formula of, 
C 600 H 960 N 154 O 179 S 3 Fe, with the immense molecular weight of 

13.332. 

Hematin. Oxy-hemoglobin is decomposed by action of 
acids or alkalies into globulins, and a colored compound con- 
taining iron, known as hematin. Hematin constitutes 4 per 
cent, of hemoglobin, and, when pure, is a metallic-looking 
powder, bluish-black in color. Two varieties of this compound 
are known, one formed by action of acids, and the other by 
action of alkalies, on hemoglobin. 

Hemochromagen is a pigment, formed by decomposition of 
hemoglobin in absence of oxygen. Its solution absorbs oxy- 
gen, and is converted into hematin. 

Hemin. Hematin unites with hydrochloric acid to form 
hematin hydrochlorate, or hemin, which produces microscopic 
crystals, in rhombic plates. p IG- 46 . 

The formation of these crys- ^ «* g. 

tals serves as a test for blood. 0? 
Hemin crystals may be ob- ^ 
tained from a dry blood smear 
on a microscope slide by add- Jw 
ing a minute fragment of so- 
dium chloride, a drop of dis- %\ 
tilled water and gently warm- * 
ing. A cover glass is then 

° Hemin Crystals. 

placed over the smear, and a 

drop of glacial acetic acid allowed to flow in from the side. 
Hemin crystals are then observed under the microscope. 
Leucocytes, or White Corpuscles. The proportion of white 



392 TEXT-BOOK OF CHEMISTRY 

to red corpuscles is about I of the former to 700 of the latter. 
The white corpuscle is grayish in color, globular or irregular 
in shape, and consists of a mass of protoplasm containing 
granules and a nucleus. Its size is about .0011 mm., or 1/2500 
inch, in diameter. 

The white corpuscles consist of 90 per cent, of water. The 
solid portion is made up of nuclein, nucleo-albumin, cell globu- 
lin, lecithin, fat, glycogen, alkaline and earthy phosphates. The 
quantity of phosphorus which they contain is relatively large. 

Blood Plaques are grayish-white disks of protoplasm floating 
in the blood stream. Their function is unknown. 

Lymph is the liquid obtained from the lymphatic vessels. 
It is a colorless, slightly alkaline liquid, having a specific 
gravity of about 1.030. Lymph contains a large number of 
white corpuscles, and it coagulates when drawn from the ves- 
sels. Lymph is composed of serum-albumin, fibrinogen, fat, 
sugar and inorganic salts. 

Muscle. The chemical composition of living muscle is a 
matter which has not been accurately determined, because 
chemical changes take place in its constituents soon after death 
and because some of the muscle constituents undergo decom- 
position in the process of analysis. According to Halliburton, 
muscle contains water, proteids including pigment, gelatin, 
fat, extractives and inorganic salts. 

If fresh muscle tissue be freed from blood, fat and con- 
nective tissue, frozen, and rubbed in a mortar, a slightly alka- 
line, or neutral, yellowish liquid can be expressed, which is 
called muscle plasma. Muscle plasma undergoes coagulation, 
yielding myosin and muscle serum. This change takes place 
in the muscle soon after death, resulting in rigor mortis. 
From muscle serum the proteids, myo-globulin and myo-albu- 
min may be obtained. From muscle plasma the proteids, para- 
myosinogen and myosinogen may be obtained ; myOsinogen is 



PHYSIOLOGICAL CHEMISTRY 393 

converted into myosin in muscle coagulation, but both of these 
proteids enter into the formation of muscle clot. A coagulating 
enzyme, known as myosin ferment, is found in muscle plasma. 

The extractives of muscle are, creatin, creatinin, xanthin, 
carnine, urea, uric acid, carnic acid, glycogen, dextrose, inosite, 
fat and lactic acid. The inorganic salts are chiefly phosphates 
of potassium, and small quantities of sodium bicarbonate ; salts 
of calcium, iron and magnesium. 

Bone contains a large percentage of inorganic constituents. 
In dried bone the inorganic matter amounts to 69 per cent. 
In children the percentage of organic matter is greater than 
in adults, and, as a result, the bones of the former are less 
liable to fracture. 

The inorganic constituents of bone are, tricalcium phosphate, 
magnesium phosphate, calcium carbonate, calcium fluoride, 
soluble salts and traces of iron. 

The proteid constituent of bone is ossein, which yields gela- 
tine when boiled with dilute hydrochloric acid. 

Teeth contain the largest percentage of inorganic matter 
of all body tissues, the enamel being the most dense. 

The dentine forms the chief mass of the tooth, being covered 
by enamel at the crown and neck, and covered by cement at the 
fang. Cement has nearly the same composition as bone. 
Dentine contains, in woman, 72.39 per cent, of inorganic mat- 
ter ; in man, 79.00 per cent, of inorganic matter. 

Enamel is an exceedingly dense substance, having the fol- 
lowing composition : Water and organic matter, 3.6 per cent. ; 
calcium phosphate and calcium fluoride, 86.9 per cent. ; mag- 
nesium phosphate, 1.5 per cent.; calcium carbonate, 8.0 per 
cent. 

Tartar is a substance which deposits on the teeth from the 
alkaline saliva. It consists of calcium phosphate, calcium car- 
bonate, organic matter and bacteria. 



394 TEXT-BOOK OF CHEMISTRY 

Hair, Nails, Feathers, Horns, Hoofs, etc., are made up of 
cholesterine and bodies containing nitrogen, called keratins. 
The keratins are probably mixtures of compounds. 

DIGESTION. 

The term, digestion, refers to the physical and chemical 
changes which take place in food in the alimentary canal in 
health. These changes begin in the mouth and they continue, 
with varying degree of intensity, throughout the entire length 
of the food canal. 

The process of digestion is directed to the solution of nutritive 
principles of food, to its conversion into absorbable forms, to 
its separation from insoluble and worthless constituents, and 
to the extrusion of the latter from the body. The study of the 
process is divided into mouth, stomach and intestinal digestion ; 
though the three processes are closely related and inter-de- 
pendent. 

In Mouth Digestion the food undergoes mechanical divis- 
ion, and it is thoroughly mixed with saliva by the action of the 
teeth and tongue. The action of saliva is to begin the digestion 
of starchy foods, partly converting them into sugar. 

Saliva is the active digestive fluid of the mouth; it is the 
mixed secretion of the parotid, submaxillary and sublingual 
glands. Saliva is a viscid, opalescent, frothy liquid; its reac- 
tion is usually alkaline, though it may be neutral or acid from 
fermentation of food particles, or in disease ; its specific gravity 
is 1.003 to 1.006. In composition, saliva consists of 99.5 parts 
water, and the solid portion is made up of epithelium, soluble 
organic matter, potassium sulphocyanate and inorganic salts. 

The soluble organic matter is made up of mucin, globulin 
and serum albumin. The inorganic constituents, besides potas- 
sium sulphocyanate, are calcium, sodium and magnesium phos- 
phates, sodium chloride and carbonate and potassium chloride. 



PHYSIOLOGICAL CHEMISTRY . 395 

The daily quantity of saliva is estimated to be 1305 grams, 
or 2.8 pounds. 

Ptyalin is the digestive ferment of saliva, and it occurs as 
a part of the soluble organic constituents. It is present in all 
animals except those which are purely carnivorous ; its action 
is to convert starch into sugar, which can be easily shown by 
adding saliva to mucilage of starch, keeping the temperature 
at 40 C, and then testing the liquid. 

Ptyalin acts best in a weak alkaline solution, though its 
action is not arrested by a weak acid solution. The activity 
of ptyalin is destroyed by the presence of strong acids or 
alkalies. 

The changes which occur in the conversion of starch into 
sugar by ptyalin consist in the addition of water, or hy- 
drolysis. Soluble starch is first formed, and this is converted 
into erythrodextrin and maltose ; erythrodextrin is further con- 
verted into acroodextrin and maltose. Erythrodextrin gives 
a red color with iodine ; acroodextrin gives no color. 

Stomach Digestion. The food passes from the mouth, 
through the esophagus, into the stomach. Salivary digestion 
of starches continues for about twenty minutes to half-an-hour, 
until the alkaline saliva is neutralized and considerable free 
hydrochloric acid is formed. 

In the stomach the food is converted into a turbid liquid, 
called chyme, by the action of gastric juice and the muscular 
movements of this organ, aided by such fluids as have been 
ingested. 

Absorption through the stomach walls takes place only to a 
limited extent, being confined chiefly to the water, inorganic 
salts and sugar. 

Gastric Juice is the digestive fluid of the stomach. It is 
secreted, as a result of the mechanical and chemical stimulus of 
substances introduced as food, by glands situated in the stom- 



396 TEXT-BOOK OF CHEMISTRY 

ach walls. A strong desire for food, or certain reflex nervous 
impulses, such as those produced by pleasant odors of prepared 
food, are said to stimulate secretion of gastric juice : strong 
emotion, as fear, anger, or grief, diminish the secretion. 

Gastric juice is a clear, colorless, acid liquid; its specific 
gravity is 1 .002 to 1 .005 ; it has a saline and acid taste ; it 
resists putrefaction and acts as an antiseptic. Gastric juice 
contains water, organic matter, hydrochloric acid; calcium, 
sodium, and potassium chlorides ; calcium, magnesium and 
ferric phosphates. The organic matter is made up of mucin, 
a proteid, pepsin and rennin, or pexin. Pepsin and pexin are 
formed by action of hydrochloric acid upon pepsinogen and 
pexinogen, zymogen bodies formed by the secretory cells. 
Hydrochloric is the normal acid of the stomach, though gastric 
juice frequently contains lactic and acetic acids, which are be- 
lieved to be due to fermentation. The quantity of hydrochloric 
acid varies, but it occurs to the extent of .1 to .4 per cent. 

The action of gastric juice on ingested foods is that of an 
antiseptic, preventing putrefaction ; and that of a digestant, 
converting proteids into peptones. 

The digestion of proteids is a progressive form of chemical 
change, resulting first in the formation of acid albumen, which 
is split into the primary proteoses, proto-albumose and hetero- 
albumose. These primary proteoses are further changed into 
secondary proteoses, consisting of two corresponding deutero- 
albumoses, which in turn are converted into two corresponding 
peptones called hemi-peptone and anti-peptone — sometimes 
designated ampho-peptones. These changes are believed to 
be due to the action of pepsin upon acid albumen. 

Rennin (or pexin), is the milk-curdling ferment of the gas- 
tric juice. 

The product of stomach digestion, called chyme, passes 
through the pyloric orifice into the duodenum. . This trans- 
fer takes place in small portions at a time, until the stomach 
is emptied of its contents. 



PHYSIOLOGICAL CHEMISTRY * 397 

Chyme is acid in reaction ; it consists of water, inorganic 
salts, acidified proteids, hemi-peptone, anti-peptone, carbohy- 
drates, liquefied fats, and indigestible portions of food. This 
acid liquid is neutralized by the alkaline intestinal secretions, 
and some of its contents are precipitated. When this occurs, 
stomach digestion ceases and intestinal digestion begins. 

Examination of Stomach Contents, To obtain a speci- 
men for examination a test meal is given, on an empty stomach, 
of a few ounces of bread and a cup of water or weak un- 
sweetened tea. After the lapse of an hour, the contents of the 
stomach are withdrawn with the stomach-tube, and filtered. 
If the fluid is too thick, it may be diluted with a definite quan- 
tity of water. 

The examination consists of a determination of reaction, of 
free acids, of free hydrochloric acid, of lactic acid, of pepsine, 
rennin, proteids, carbohydrates ; estimation of total acidity, of 
free acids, of free hydrochloric acid, of combined hydrochloric 
acid, of total organic acids. 

1. Reaction is determined by use of litmus-paper, and in the 
normal secretion it should always be acid. 

2. Detection of Free Acids may be accomplished by use of 
congo-red paper. A drop of the fluid placed on a piece of this 
paper produces a blue color if free acids are present. 

3. Free Hydrochloric Acid may be recognized by a number 
of tests : 

(a) Methyl- violet in strong aqueous solution, added to the 
gastric juice, produces a change of violet to blue in presence 
of free HC1. 

(b) Resorcin solution, obtained by dissolving 5 parts re- 
sorcin, 3 parts cane sugar, in 100 of diluted alcohol, gives a 
bright red color in presence of hydrochloric acid when warmed. 
The test is applied by adding 5 drops resorcin solution to an 
equal quantity of gastric juice and warming gently ; as the 
liquids evaporate, a bright red color appears. 



398 TEXT-BOOK OF CHEMISTRY 

(c) Dimethyl-amido-azobenzol in .5 per cent, solution in 
alcohol, mixed with the gastric juice, gives a cherry-red color. 
This test is so sensitive as to show so little as .002 per cent, 
hydrochloric acid. 

4. Lactic Acid may be recognized by mixing 2 c.c' UfTel- 
mann's reagent with 2 c.c. of the gastric juice ; in the presence 
of lactic acid it gives a yellow color. 

Since the presence of other bodies sometimes interferes with 
this reaction, it is well to extract 10 c.c. of gastric juice with 
50 c.c. of ether, evaporate the ethereal solution (which contains 
the lactic acid) to dryness, add a few drops of water to the 
residue, and then apply the test. 

UfTelmann's reagent is prepared by adding two drops ferric 
chloride solution to 10 c.c. of one per cent, carbolic acid solu- 
tion, and diluting with water to a pale blue color. 

5. Pepsin in presence of free hydrochloric acid may be 
recognized by its power to digest dried fibrine. Ten c.c. of 
the gastric juice is placed in a test-tube, the fibrin added, and 
the temperature kept at 40 ° C. ; in presence of pepsin the fibrin 
rapidly dissolves. 

6. Rennin may be recognized by neutralizing 10 c.c. of gas- 
tric juice with N/10 potassium hydroxide solution, and mixing 
with 10 c.c. fresh milk. The mixture kept at 40 C. should 
form a coagulum in fifteen minutes if rennin be present. 

7. The proteids likely to be found in gastric juice are syn- 
tonin, albumoses and peptone. 

Syntonin precipitates when the gastric juice is neutralized; 
the precipitate is soluble in acids or alkalies. 

Albumoses are precipitated by saturated solution of ammo- 
nium sulphate. 

Peptones may be recognized by making the gastric juice 
strongly alkaline with potassium hydroxide and. adding a few 
drops of solution of cupric sulphate (1 to 1,000). With this 
solution peptones produce a red color. 



PHYSIOLOGICAL CHEMISTRY 399 

8. Starch may be recognized by the blue color it gives with 
iodine solution. The same reagent gives a brownish-red color 
with erythrodextrin, and has no effect upon acroodextrin. 

Quantitative Tests. 

1. Estimation of Total Acidity may be accomplished by add- 
ing a few drops of phenolphthalein solution to 10 ex. of the 
filtered gastric juice, and titrating with N/io sodium hydroxide 
solution. 

The results are expressed in the percentage of c.c. sodium 
hydroxide used, thus : Forty per cent, acidity indicates that 
40 c.c. N/10 NaOH are required to neutralize ioo c.c. of gastric 
juice. One c.c. N/io NaOH neutralizes .00365 gm. hydro- 
chloric acid. If 4 c.c. N/io NaOH be required to neutralize 
10 c.c. gastric juice, it would correspond to 4 times .00365 
hydrochloric acid, or .01456 gm. hydrochloric acid in 10 c.c. 
of the solution tested, or 0.146 per cent. 

2. The Total Quantity of Free Acids may be estimated by 
adding congo-red as an indicator and titrating 10 c.c. gastric 
juice with N/io sodium hydroxide until a blue color is pro- 
duced. Congo-red is unaffected by acid salts, and thus shows 
the quantity of free acids only. 

3. Free Hydrochloric Acid may be determined by adding 5 
drops dimethyl-amido-benzol solution (solution to be made as 
above described) to 10 c.c. of gastric juice, as an indicator, and 
titrating with N/io sodium hydroxide solution : disappearance 
of the red color indicates end of the reaction. By deducting the 
quantity of free hydrochloric acid from the quantity of total 
free acids, the quantity of free organic acids is determined. 

4. Combined Hydrochloric Acid may be estimated by first 
titrating K) c.c. gastric juice, using 3 drops 1 per cent, solution 
alizarine as an indicator, with N/io sodium hydroxide solu- 
tion : a violet color indicates end of the reaction. The acidity 



400 TEXT-BOOK OF CHEMISTRY 

determined here is due to free hydrochloric acid, acid salts and 
organic acids ; the difference between this and the total acidity 
indicates the quantity of combined hydrochloric acid. 

5. Difference between the estimated quantity of combined 
hydrochloric acid and free hydrochloric acid shows acidity due 
to organic acids and acid salts. 

Intestinal Digestion. The intestinal fluids are alkaline in 
reaction and are made up of the pancreatic juice, intestinal juice 
and bile. 

The pancreatic gland produces two secretions: one is an 
internal secretion, and passes directly into the blood to regulate 
the assimilation of carbohydrates ; the other, the pancreatic 
juice, passes into the intestine to take part in digestion. 

Pancreatic Juice is a slightly opaque, viscid, alkaline liquid ; 
it contains about 5 per cent, of solids, two thirds of which are 
organic in character. Of the inorganic salts, sodium carbonate 
is the most important constituent. 

Among the organic constituents of pancreatic juice, a num- 
ber of ferments are found; these are: Amylopsin, which con- 
verts starch into sugar ; Trypsin, which converts proteids into 
peptone, in alkaline solution ; Steapsin, which decomposes fats 
into fatty acids and glycerin, and which emulsifies fats ; and a 
milk-curdling ferment. 

On account of the presence of so many different ferments, 
the pancreatic juice is capable of a more extended digestive 
action than any of the other alimentary fluids. It acts upon 
carbohydrates, fats and proteids. 

Starch is converted into maltose and dextrose, by the fer- 
ment amylopsin, passing through the intermediate stages of 
dextrin formation, similar to those of salivary digestion. The 
action of amylopsin is much more energetic than that of 
ptyalin. 

Fats are decomposed by the ferment steapsin, with forma- 



PHYSIOLOGICAL CHEMISTRY ' 4OI 

tion of fatty acids and glycerine. The liberated fatty acids 
form soaps with sodium carbonate of the pancreatic juice, and 
also with cholesterin of the bile. This mixture of compounds 
serves to aid in the emulsification of undecomposed fats. 

Proteids are converted into peptones by aid of the ferment 
trypsin. The first change taking place in proteids is the for- 
mation of alkali-albumen, and the end products are, peptone, 
leucin, tyrosin and aspartic acid. The intermediate stages of 
the conversion have not been accurately determined, but it 
is believed that the alkali-albumen is converted into deutero- 
proteoses, and this into peptone. Since half of the peptone is 
decomposed by further digestion into leucin, tyrosin and 
aspartic acid, and the other half remains unchanged, the pep- 
tone is thought to be of two kinds, which are called anti-pep- 
tone and hemi-peptone. This corresponds to two forms of 
secondary proteoses (deutero-proteose) as found in stomach 
digestion. 

Primary proteoses (proto-albumose and hetero-albumose) 
are not found as a result of pancreatic digestion. Proteid 
digestion begins in the stomach and is finished in the intestine. 

Alkali-Albumin 
/ I \ 



/ 

/ 


PROTEID \ 

\ 

Acid-Albumin \ 


/ / \ \ 

/ / \ \ 

/ / \ \ 

/ Proto-albumose. — ( Primary proteoses. ) — Hetero-albumose. \ 

/ / \ \ 

/ / \ \ 

/ / \ \ 

=Deutero-albumose — (Secondary proteoses) — Deutero-albumose.= 


1 
(Anti) Peptone. 


— (Ampho-peptones) — (Hemi) Peptone. 



Leucin, tyrosin, aspartic acid. 
Diagrammatic illustration of gastric and pancreatic digestion of proteids. 
27 



402 TEXT-BOOK OF CHEMISTRY 

Intestinal Juice, secreted by the intestinal glands, takes a 
part in digestion of which very little is known. Experiments 
indicate that it serves to complete the conversion of carbohy- 
drates into glucose and levulose, by action of a ferment called 
invertin. 

Bile is secreted by the liver cells. It is poured into the in- 
testine along with the pancreatic juice, and aids the process of 
digestion, particularly in the emulsification and absorption of 
fats. 

Bile is a green or golden-yellow, somewhat viscid liquid ; its 
reaction is alkaline; its specific gravity is from i.oio to 1.020; 
it has a bitter taste. The daily quantity is said to be 1000 to 
1700 c.c, most of which is reabsorbed from the intestinal walls. 
Bile contains from 7 to 20 per cent, of solids, as follows : 
Sodium glycocholate and sodium taurocholate, fats, soaps, 
cholesterin, mucus, pigment, lecithin. 

The Normal Bile Pigments are bilirubin and biliverdin ; they 
impart a green and red color, respectively. Bilirubin is formed 

from hematin of the red coloring 
matter of the blood. Hematin 
combines with water and looses its 
iron, in the liver, forming biliru- 
bin. Bilirubin undergoes oxida- 
tion in the gall-bladder, forming 
biliverdin. 

Cholesterin, Co 7 H 45 OH, has the 

Cholesterin Crystals. 

structure of an alcohol, but on 
account of its greasy character and solubility in ether, it has 
been classed as a fat. Cholesterin is always found in bile, but 
it occurs in the blood, brain, nervous tissues and other parts 
of the body. It is found, also, in the vegetable kingdom. 
Cholesterin occurs in transparent, thin, rectangular crystals ; it 
is held in solution in the bile by presence of the bile salts ; when 




PHYSIOLOGICAL CHEMISTRY 403 

these are deficient, it sometimes deposits in the gall-bladder, 
forming gall-stones, which are more or less colored by altered 
bile pigments. Cholesterin is discharged from the body as 
stercorin in the feces. 

Sodium Glycocholate and Sodium Tanrocholate are com- 
pounds formed by replacement of hydrogen in glycocholic acid, 
C 26 H 43 N0 6 , and taurocholic acid, C 26 H 45 N0 7 S, with sodium. 

Glycocholic Acid may be decomposed into glycocol, or amido- 
acetic acid, CH 2 NH 2 C0 2 H, and cholic acid, C 24 H 40 O 2 . 

Taurocholic Acid decomposes into taurine, or amido-ethyl- 
sulphonic acid, C 2 H 4 NH 2 HS0 3 , and cholic acid. These de- 
compositions are effected by heating with dilute acids or alka- 
lies ; they also occur in the intestines. 

The Fermentative and Putrefactive Changes taking place in 
the intestines result in the formation of lactic acid, butyric acid, 
carbon dioxide and hydrogen, from fats ; valerianic acid, ammo- 
nia and carbon dioxide, from leucin ; indol from tyrosin, ante- 
cedent to indican of the urine. Skatol is also formed from 
proteids and gives rise to the odor of feces, along with other 
substances, such as hydrogen sulphide and organic acids. 

Fecal Matter consists of the indigestible portions of food, 
the useless products of digestion, epithelium, residuum of in- 
testinal juices and excretions from the blood. The normal 
daily quantity varies from four to six ounces. 

RESPIRATION. 

Respiration is the act which furnishes a supply of oxygen 
to the tissues and removes carbon dioxide. The consumption 
of oxygen and formation of carbon dioxide in the tissues is 
called internal respiration, and it takes place as a part of 
tissue metabolism. Oxygen is carried in arterial blood from 
the lungs to the tissues, and carbon dioxide is returned in 
venous blood from the tissues to the lungs. In the lungs, an 



404 TEXT-BOOK OF CHEMISTRY 

exchange of gases between the blood and inspired air takes 
place, which is called external respiration. 

The changes taking place in the composition of respired air 
consequently relate to the quantities of oxygen and carbon 
dioxide. Inspired air contains, by volume, 20.8 per cent, of 
oxygen ; 79.2 per cent, of nitrogen ; traces of carbon dioxide 
(.04 per cent.) ; and a variable quantity of watery vapor. Ex- 
pired air contains, 16.02 per cent, of oxygen; 79.6 per cent, of 
nitrogen ; 4.38 per cent, of carbon dioxide ; watery vapor to 
saturation, and organic matter. The quantity of oxygen lost 
amounts to 4.78 per cent., and the quantity of carbon dioxide 
gained amounts to 4.38 per cent. The gain in organic matter 
is variable, and the same may be said of watery vapor, the 
latter depending upon variations in the temperature of respired 
air. 

The oxygen of respired air enters into the alveoli of the 
lungs, during respiration, and is taken up by the blood circu- 
lating in capillary vessels surrounding the alveoli. In the 
blood the larger portion of oxygen is in combination with 
hemoglobin, though a small portion is also contained in the 
blood plasma. Oxy-hemoglobin imparts the bright red color 
to arterial blood, and gives up its oxygen in passing through 
the capillary vessels of the tissues. Reduced hemoglobin passes 
into the veins, from the capillaries of the tissues, and imparts 
the dark red color to venous blood. 

Carbon dioxide exists in the blood partly dissolved and partly 
combined with the salts of the plasma. It is derived from the 
tissues of the body as the blood-stream passes through in ca- 
pillary vessels, and it is carried to the lungs in the returning 
venous blood. Carbon dioxide is eliminated from the blood into 
the alveoli of the lungs and passes out as a constituent of 
expired air. 



PHYSIOLOGICAL CHEMISTRY m 405 

MILK. 

Milk is the secretion of the mammary gland of the female, 
intended for the nutrition of the nursing mammal. It contains 
all the food principles, both organic and inorganic, in proper 
proportion for the sustenance and development of the young 
animal for a limited period of its life. The composition of 
milk consequently varies in different animals, in regard to the 
relative proportion of its constituents, according to the needs 
of the species ; it also varies in the same animal under varying 
conditions of food and health. 

Cow's milk, a typical milk, is of interest because it is so 
largely used as an article of food ; human milk is of interest on 
account of its relation to the nutrition of the infant. 

A number of analyses of cow's milk and human milk show 
an average composition, as follows : 

Cow's Milk. Human Milk. 

Water 86.70 88.30 

Proteids (casein and albumin) 4.40 2.00 

Fat 3-65 340 

Milk sugar 4-50 6.00 

Inorganic salts 0.75 0.30 

In addition to the above inorganic constituents, milk con- 
tains a number of extractives in very small amount, viz. : 
Lecithin, creatin, urea, citric acid and phospho-carnic acid. 

The gases of milk are, carbon dioxide, 7.06 per cent. ; oxygen, 
0.1 per cent. ; nitrogen, 0.7 per cent., by volume. 

Milk is an opaque, white liquid. The inorganic salts, pro- 
teids and lactose are in solution. The fat is in suspension in 
the form of small globules, having a diameter varying from 
.0015 mm. to .005 mm., in a condition in which they do not 
spontaneously coalesce. The properties of fat-globules indi- 
cate that they have a fluid proteid envelope. The specific 
gravity of normal milk varies from 1 .028 to 1 .035 ; its reaction 



406 TEXT-BOOK OF CHEMISTRY 

in herbivorous animals and the human subject is alkaline; in 
the carnivora it is acid. 

The Inorganic Salts are made up of sodium, potassium, cal- 
cium and magnesium, chlorides and phosphates, and a small 
amount of iron. 

The Chief Proteid of milk is caseinogen ; lacto-albumin and 
lacto-globulin are found associated with it in small amount. 
Caseinogen may be precipitated by saturating milk with acetic 
acid, magnesium sulphate or sodium chloride. 

Caseinogen may be obtained as follows : Saturate milk with 
sodium chloride, thus precipitating caseinogen and fat; filter, 
wash the precipitate with saturated solution of sodium chloride, 
rub moist precipitate with water and allow to stand twenty- 
four hours, and filter. Caseinogen is contained in the filtrate. 
A portion of the solution treated with acetic acid gives a pre- 
cipitate of caseinogen ; another portion treated with rennin, 
calcium chloride and heat (40 C.) precipitates para-casein. 

To separate lacto-globulin and lacto-albumin, proceed as fol- 
lows : Saturate a portion of the milk with sodium chloride and 
filter, to the filtrate add magnesium sulphate to saturation ; 
lacto-globulin precipitates. Filter and add to the filtrate ammo- 
nium sulphate to saturation ; lacto-albumin precipitates. 

The action of rennet upon milk results in the cleavage of 
caseinogen into casein, an insoluble proteid, and a small quan- 
tity of a soluble proteid. This cleavage is indicated by the for- 
mation of a coagulum, consisting of casein, and the insoluble 
proteid, with fat globules entangled in the coagulated mass. 
The coagulation does not occur in the absence of calcium salts. 

The liquid portion of coagulated milk is called whey, and it 
contains water, salts, lacto-albumin and milk-sugar. The solid 
portion is called curd, and consists of casein and fat. 

Milk-sugar belongs to the saccharose group and has the for- 
mula, C 12 H 22 11 .H 2 0. By action of the lactic acid ferment 



PHYSIOLOGICAL CHEMISTRY 407 

it is readily converted into lactic acid and carbon dioxide. The 
formation of lactic acid in milk gives a sour taste and causes 
the precipitation of caseinogen. Milk-sugar is dextro-rotatory ; 
it yields galactose and dextrose by hydrolysis. 

Milk- fat may be removed by shaking with ether after the 
addition of a few drops of solution of caustic alkali to dissolve 
the proteid envelope of the fat-globules. 

Milk-fat is a mixture of the glycerides of palmitic and oleic 
acids, chiefly, with smaller quantities of butyric, stearic, caproic 
and caprillic acids. 

The fat-globules of milk do not cohere spontaneously, but 
they may be made to 1 do so after the formation of lactic acid 
in milk, by churning. Butter represents the milk fat, containing 
a small percentage of water, traces of casein, salts and coloring 
matter. 

Human Milk differs from cow's milk, as may be seen in the 
preceding analysis, in that cow's milk contains over twice as 
much proteid and inorganic salts, and nearly a third less of 
milk-sugar. The casein of human milk is more readily soluble 
in gastric juice, and the precipitate of para-casein is more finely 
divided than in cow's milk. The casein of human milk con- 
tains less of carbon, nitrogen and phosphorus, but more of hy- 
drogen, sulphur and oxygen, than cow's milk. Human milk is 
said to contain a proteid called opalisin, which is rich in sulphur, 
and which is not found in other milk. 

THE URINE. 

The urine is an excretion derived from the blood by the 
Malpighian corpuscles and uriniferous tubules of the kidney. It 
is an aqueous solution of organic and inorganic constituents, 
which are formed during tissue metabolism, and represent the 
waste products of cellular activity. 

Normal human urine, when fresh, is a clear, transparent 



408 TEXT-BOOK OF CHEMISTRY 

liquid; it has a pale yellow or amber color and an aromatic 
odor ; its reaction is acid ; its specific gravity is 1 .020. 

The urine upon standing will form a thin, cloudy film of 
mucus, which gradually sinks to the bottom of the vessel; 
the acid reaction increases, and, if the urine be concentrated, a 
deposit of urates or uric acid gradually forms. After a time, 
if the temperature be slightly elevated, the urine gradually 
undergoes decomposition by the presence of micro-organisms. 
This change is largely due to the micrococcus urece and the 
bacterium urecs. If left at rest, the urine frequently forms a 
thin, lustrous film on the surface, which is composed of bacteria 
and vegetable growth. An ammoniacal odor develops from the 
formation of ammonium carbonate from decomposing urea. 
The reaction becomes alkaline and a turbidity results from 
precipitation of earthy phosphates, ammonio-magnesium phos- 
phate and ammonium urate. 

The conversion of urea into ammonium carbonate is accom- 
plished by the action of bacteria. The bacteria cause a mole- 
cule of urea to combine with two molecules of water, as shown 
in the following equation : 

CO(NH 2 ) 2 + 2H 2 0= (NH 4 ) 2 C0 3 . 

The composition of urine is shown in the following analysis 
according to Brubaker : 

Water 1,500.00 cc. 

Total solids 72.00 gm. 

Urea 33-i8 gm. 

Uric acid (urates) 0.55 gm. 

Hippuric acid (hippurates) 0.40 gm. 

Kreatinin, xanthin, hypoxanthin, guanin, 

ammonium salts, pigment, etc 11.21 gm. 

Inorganic salts: Sodium and potassium 
sulphates, phosphates and chlorides; 

Mg and Ca phosphates 27.00 gm. 

Sugar a trace. 

Gases: Nitrogen and carbonic acid. 



PHYSIOLOGICAL CHEMISTRY - 409 

The composition of urine, given in the above analysis, varies 
greatly with varying conditions. It is influenced by the degree 
of activity of the subject, the time of day, temperature, age, 
sex, &c. 

Physical Properties. 

The daily quantity of urine passed varies with varying 
conditions of food, drink, temperature, health and disease. It 
averages, in the normal healthy adult, from 1,000 to 1,500 c.c. 
(36 to 54 fluid ounces). The daily quantity of total solids varies 
from 55 to 60 grams (840 to 920 grains). 

The Color of urine varies from pale yellow or colorless to 
reddish-brown, but it is usually of an amber color. A smoky, 
reddish urine indicates the presence of blood ; a brownish-green 
indicates presence of bile ; colorless urine in large quantity 
indicates presence of sugar. 

The color of urine is affected by certain articles of diet and 
certain drugs. It is darkened by large quantities of meat and 
coffee; beets produce a reddening effect; carrots produce a 
brown color; rhubarb and senna, a reddish-yellow. Large 
doses of salicylic acid color the urine green ; carbolic acid pro- 
duces a dark or black coloration. 

The Urinary Pigments are : Urobilin, urochrome, and uro- 
erythrin. They are believed to be produced from bilirubin of 
the liver. The presence of indican, from intestinal fermenta- 
tion, also gives rise to color when the urine is exposed to the 
air or acted upon by reagents. 

Urochrome imparts a yellow or orange color. It may be 
precipitated by ammonium sulphate, and the precipitate when 
decomposed by an acid gives a dark, brown substance. 

Urobilin imparts a reddish-brown color. It is increased by 
conditions which cause destruction of hemoglobin in the body, 
in high fever and in cirrhosis of the liver. 



4IO TEXT-BOOK OF CHEMISTRY 

Uroerythrin imparts the pink or red color to urine. It is said 
to be increased by excessive eating, alcoholic excesses, malaria, 
pneumonia, excessive perspiration and great muscular exertion. 
Its presence in excessive quantity is indicated by the appear- 
ance of a pink color in the precipitate caused by adding a solu- 
tion of barium chloride to' the urine. 

Odor. Fresh urine has a pleasant, aromatic odor, believed 
to be due to the presence of volatile acids and ethers. The dis- 
agreeable ammoniacal odor is due to the products of decom- 
position, and if this is present at the time the urine is passed 
it indicates that decomposition has taken place inside the body. 
The decomposition of urine containing albumen or pus may 
give rise to the formation of hydrogen sulphide. 

Odors are imparted to the urine by ingestion of certain arti- 
cles of food, such as asparagus, cabbage, cauliflower, parsnips 
and onions or garlic. 

Reaction. In normal, fresh urine the reaction is usually acid. 
The acidity is due to the presence of mono-sodium .hydrogen 
phosphate, NaH 2 P0 4 . The reaction finally becomes alkaline 
upon standing, when ammoniacal decomposition has taken 
place. 

The acidity of urine is diminished or disappears after a full 
meal, especially of a vegetable diet ; it is increased by excessive 
meat diet, and by prolonged muscular exercise. 

Alkaline acetates, tartrates and citrates increase the alkalinity 
of the urine; benzoic and boric acids increase the acidity. 

Alkalinity due to the presence of ammonia may be recognized 
by the return of the red color of litmus upon drying, after it 
has been dipped into the urine. 

Specific Gravity. The specific gravity of normal urine aver- 
ages about i. 020 (1.021 1 ), though it may vary in health from 
1. 01 2 to 1.030. In determining the specific gravity it must be 

1 Ogden. 



PHYSIOLOGICAL CHEMISTRY 



411 



Fig. 48. 




remembered that the daily quantity of the urine must be taken 
into consideration in order to properly estimate its value. A 
urine may have a high specific gravity on account of a limited 
consumption of fluids and excessive perspiration, or a low 
specific gravity may be occasioned by the opposite conditions. 

A long continued variation from 
the normal should excite the sus- 
picion of disease. In diabetes in- 
sipidus the specific gravity may 
range as low as 1.001 or 1.002, while 
in diabetes mellitus it is usually 
high, sometimes reaching 1.050. On 
the other hand, the specific gravity 
of diabetic urine may be normal or 
below on account of the excessive 
amount of fluid excreted by the kid- 
ney. 

The determination of specific 
gravity is made by the use of a 
specially constructed hydrometer, 
known as a urinometer, the scale of 
which is graduated from 1.000 to 
1.060. This instrument is made to 
float in the urine in a narrow glass 
vessel, when the specific gravity may 
be read from the scale ; care should 
be taken to prevent the urinometer 
from coming in contact with the 
sides of the containing vessel. The 
temperature at which the determina- 
tion is to be made is usually marked on the instrument, and 
should, of course, be duly regarded. 

Total Solids. In the healthy adult male the daily quantity 



1000 
1005 

I0f0 

1015 

ioao 

1025 
I03O 
1035 
1040 
J045 



• 



Urinometer. 



4 12 TEXT-BOOK OF CHEMISTRY 

of total solids amounts to about 70 to 73 grams, of which, 
nearly one-half is urea, one-fifth chlorides, and one-twenty- 
fifth phosphates. 

The total solids per 1,000 c.c. of urine may be estimated 
approximately by multiplying the last two figures of the specific 
gravity by the coefficient of Haeser, which is 2.33, the product 
being expressed in grams. For example, suppose the specific 
gravity of the urine to be 1.020; the solids per 1,000 c.c. 
would be 

20 X 2.33 = 46.60 grams. 

If the daily quantity of urine were 1,500 c.c, then the total 
solids in this amount of urine would be 

46.60 

X 1500 = 69.9 grams. 

1000 

The total solids of urine may be more accurately determined 
by taking 10 c.c. of the mixed 24 hours urine, placing it in a 
weighed platinum capsule and evaporating carefully to dryness 
in a vacuum over sulphuric acid. The dry residue is weighed, 
and when the weight of the dish is deducted, the remainder 
represents the weight of the total solids in 10 c.c. of urine. 
From this the solids in the whole volume of the urine may be 
calculated. 

By incinerating the dried residue and weighing the ash, the 
total inorganic solids may be determined. The difference be- 
tween the weight of the total solids and total inorganic solids, 
represents the weight of total organic solids. 

Analysis of the ash may be practiced for determination of 
inorganic constituents. Chlorine is determined by precipitating 
a solution of the ash in dilute nitric acid by adding silver 
nitrate ; sulphuric acid by barium chloride ; phosphoric acid by 
ammonium molybdate ; calcium by ammonium oxalate ; potas- 
sium by platinum perchloride ; iron by potassium f errocyanide, 






PHYSIOLOGICAL CHEMISTRY 413 

&c. Most of the inorganic constituents may be determined 
more conveniently, however, by tests applied directly to the 

urine. 

Normal Constituents. 

i. Inorganic 

Chlorides occur in the urine chiefly as sodium chloride, 
though small quantities of potassium and ammonium chloride 
are found. Chlorides constitute the chief solid constituent of 
urine next to urea. The daily quantity of sodium chloride 
eliminated in the urine varies from 10 to 20 grams. 

The chlorides in the urine are increased by increased con- 
sumption of sodium chloride ; they are diminished, or absent, 
in pneumonia ; diminished in the early stages of most acute 
diseases, and in chronic diseases attended by serous effusions. 

Detection and approximate estimation of the chlorides may 
be accomplished by taking half a wineglass of urine, with one- 
third its' volume of nitric acid in a separate layer at the bot- 
tom, and adding a drop of solution of silver nitrate (1 part to 
8 of distilled water). The presence of chlorides will be indi- 
cated by the formation of a white precipitate of silver chloride. 
If the chlorides be normal or increased, the precipitate forms a 
white ball, which falls to the bottom of the urine ; if the chlor- 
ides be diminished^ the precipitate becomes quickly diffused 
through the surrounding liquid. Albumen interferes with this 
test and, if present, it should be removed by boiling, adding a 
drop of acetic acid, and filtering. 

Estimation of Chlorine by Mohr's Volumetric Method. The 
solutions necessary for this test are: 1. A 20 per cent, solution 
of pure neutral potassium chromate in distilled water. 2. 
Standard silver nitrate solution, made by dissolving 29.075 
grams fused silver nitrate in distilled water and making up 
to 1,000 c.c. Each c.c. of this solution represents .01 gm. 
sodium chloride, or .006065 g m - chlorine. 



4H TEXT-BOOK OF CHEMISTRY 

Process. Take 10 c.c. of urine, dilute with 50 c.c. of distilled 
water, and add .5 c.c. of the potassium chromate solution. The 
mixture is now to be titrated with the standard silver nitrate 
solution, until a permanent pink color appears. One c.c. should 
be deducted from the total quantity of test solution used, so 
as to allow for the action of other bodies on the test solution. 

Phosphates. Phosphoric acid occurs in the urine combined 
with sodium and potassium, on the one hand, and with mag- 
nesium and calcium on the other. The former is known as the 
alkaline phosphates and comprises about two thirds of the phos- 
phates present ; the latter is known as the earthy phosphates, 
and comprises about one third of the total. 

The composition of these phosphates in normal acid urine 
is represented in the following formulae: 

NaH 2 P0 4 , Na 2 HP0 4 , CaHPO*, CaH 4 (P0 4 ) 2 and MgHPO*. 

The earthy phosphates frequently precipitate in an alkaline 
urine, on account of the conversion of acid phosphate of cal- 
cium and magnesium into normal salts. The grayish sediment 
so formed is often referred to as amorphous phosphates. A 
similar change is sometimes produced by boiling a feebly acid 
urine, which gives rise to a grayish-white precipitate. This 
precipitate may be mistaken for albumen, but it can be easily 
distinguished from the latter by its solubility in a few drops 
of acetic acid. Ammoniacal urine sometimes forms the, so- 
called, " triple phosphate," by the combination of ammonium 
with magnesium phosphate, MgNH 4 P0 4 . This substance is 
sometimes formed in the bladder as a result of ammoniacal de- 
composition of the urine, giving rise to the formation of uri- 
nary calculi, or " stone in the bladder." 

Earthy phosphates are precipitated by adding a solution of 
caustic alkali to the urine. 

The alkaline phosphates, being very soluble, are not so 
easily precipitated from the urine. 



PHYSIOLOGICAL CHEMISTRY ' 4 T 5 

The normal quantity of phosphoric oxide (P 2 5 ) excreted 
in the 24 hours urine is from 2.5 to 3.5 grams. 

The phosphates are increased in diseases of the bones, 
rickets, tuberculosis, diseases of the nervous system and acute 
yellow atrophy of the liver ; they are diminished in most of 
the acute diseases, diseases of the kidney, gout and pregnancy. 

Detection and Approximate Estimation of Phosphates. 

Earthy Phosphates. To half a test-tube of filtered urine 
add enough ammonia water to produce a decided alkaline re- 
action, and warm the mixture. The earthy phosphates are pre- 
cipitated as a grayish-white powder. Allow the tube to stand 
for 18 hours and if the sediment is one-fourth to one-half inch 
deep the quantity is normal ; if more than one-half inch, in- 
creased; if less than one-fourth inch, decreased. 

Alkaline Phosphates. After separating the earthy phos- 
phates, as described above, filter the liquid, add 5 cc. of mag- 
nesia mixture 1 and warm ; the alkaline phosphates form a 
white precipitate. Allow to stand for 18 hours, and if the de- 
posit be one-half to three-quarters inch deep the quantity is 
normal ; if more than three-quarters inch, increased ; if less 
than one-half inch, diminished. 

The total phosphoric acid may be estimated by taking 50 
cc. of the urine, adding a few drops of solution of calcium 
chloride and then ammonia water. The precipitate is washed 
on the filter, dried, ignited and weighed. The weight of the 
precipitate represents tricalcium phosphate, Ca 3 2P0 4 , from 
which the phosphoric acid may be calculated. 

Sulphates. Sulphates are present in the urine in two forms, 
viz. : Sodium, potassium and magnesium sulphates ; sulphates 

1 Magnesia Mixture. — Made by dissolving one part each of mag- 
nesium sulphate, ammonium chloride and ammonia water in 8 parts 
of distilled water. 



41 6 TEXT-BOOK OF CHEMISTRY 

of indoxyl, skatoxyl and phenol. The former are known as 
alkaline sulphates ; the latter, as aromatic sulphates. 

The normal daily quantity of sulphates excreted is 1.5 to 3.0 
grams, one-tenth of which is in the form of aromatic sulphates. 
The quantity may vary considerably in health : it is increased 
in acute febrile diseases ; it is diminished in chronic diseases. 

Detection and Approximate Estimation of Sulphates may be 
made according to the method of Ogden, as follows : To half 
a test-tube of the filtered urine add from one to two finger- 
breadths of barium solution, 1 a white precipitate forms, which 
in 18 to 24 hours will fill one-half the concavity of the tube 
in normal urine; if diminished, less than one-half the con- 
cavity ; if increased, more than one-half the concavity. 

Sulphuric acid is estimated by the method of Salkowski, 
viz. : 100 c.c. of the urine in a beaker is acidified with 5 c.c. of 
strong hydrochloric acid, the mixture is boiled and barium 
chloride solution is added as long as a precipitate is formed. 
The precipitate is collected on a filter, washed with hot water, 
until the washings give no precipitate with sulphuric acid ; then 
wash with hot alcohol and then with ether. Remove the filter 
and contents, and incinerate in a platinum crucible. Cool over 
sulphuric acid, weigh, deduct weight of dish and filter-ash. 
The remaining weight represents barium sulphate, BaS0 4 , 
from which SO s may be calculated — 100 parts barium sulphate 
is equivalent to 34.33 of SO s . 

Correction. A small amount of barium sulphide is formed 
in the analysis, which is corrected by adding a few drops of 
sulphuric acid after the platinum dish has cooled, and heating 
again to redness, to drive off excess of sulphuric acid. 

2. Organic. 
Urea, Carbamide, CO(NH 2 ) 2 . Urea is by far the most 
important of the organic constituents of urine. It represents 

1 Barium solution is made by dissolving barium chloride, 4 parts; 
strong hydrochloric acid, 1 part; in 16 parts of distilled water. 



PHYSIOLOGICAL CHEMISTRY 417 

the end product of proteid metabolism, and is obtained solely 
from animal sources. It occurs in small amount in various 
tissues of the body, viz. : Muscle, blood, chyle, lymph, bile and 
other fluids. It contains 85 to 90 per cent, of the total nitrogen 
of urine. 

Urea may be prepared by evaporating a convenient quantity 
of urine to a syrupy consistency and adding an equal volume 
of nitric acid to the cooled liquid. The urea separates in the 
form of crystals of the nitrate of urea, which may be decom- 
posed into urea and barium nitrate, by adding barium carbonate. 

In properties, urea is a solid, forming colorless, prismatic 
crystals which have a cooling", bitter taste, resembling potas- 
sium nitrate. It dissolves in water and fuses when moderately 
heated (130 C), but it decomposes at a high temperature, 
forming ammonia gas and water vapor. 

Urea undergoes decomposition when boiled with water, and 
the decomposition is facilitated by pressure, forming ammonia, 
carbon dioxide and water, thus : 

CO ( NH 2 ) 2 + 2H 2 = C0 2 + 2NH3 + H 2 0. 

Hypobromites and hypochlorites of the alkalies cause its de- 
composition, forming hydrochloric acid, carbon dioxide and 
nitrogen. Upon this reaction the most important method for 
its quantitative estimation is based. The decomposition is 
effected by the bromine or chlorine of these compounds, thus : 

CO ( NH 2 ) 2 + 6Br = H 2 + 6HBr + C0 2 + N 2 . 

Urea forms salts with acids, retaining the hydrogen like 
alkaloids. 

The quantity of urea under normal conditions in the 24 hours 
urine varies from 17 to 40 grams (usually from 30 to 40 gm.). 

Urea is diminished in health when the diet is comparatively 
free from nitrogenous food, following excessive perspiration, 
sometimes in pregnancy, after taking small doses of quinine, 
28 



4i8 



TEXT-BOOK OF CHEMISTRY 



following the ingestion of excessive quantities of water for 
a long time. It is diminished in disease, in most of the kidney 
diseases, in degenerative changes of the liver, in acute febrile 
diseases following the acme of the disease and in convales- 
cence, in diseases attended with serous effusion, preceding death 
from any cause, excessive vomiting and (Jiarrhea. 

tj. Urea is increased in 

■tig. 49. 

health by over-feeding, by 
great muscular exertion, by 
ingestion of ammonium 
compounds, by hot baths. 
It is increased in disease in 
the early stages of febrile 
diseases, in diabetes in- 
sipidus, in diabetes mel- 
litus, sometimes in chronic 
interstitial nephritis, in 
chronic gout. 

Urea May be Detected in 

Urine. I. By adding to 

the urine an equal volume of solution of sodium hypobromite ; 

effervescence takes place in the presence of urea from the 

escape of nitrogen gas. 

2. To a drop of urine on a glass slide add a drop of pure 
nitric acid and allow the liquid to evaporate. Crystals of urea 
nitrate may be seen under the microscope. 

Estimation of Urea. Several methods have been devised 
for the quantitative estimation of urea, the simplest and most 
convenient of which is the hypobromite method of Knop. This 
is based upon the decomposition of urea, in urine, by alkaline 
sodium hypobromite solution, and the measurement of the 
volume of nitrogen evolved. In this decomposition, nitrogen, 
carbon dioxide and water are formed, as shown in the equation : 




Urea Nitrate. (Coblentz.) 



PHYSIOLOGICAL CHEMISTRY. 



419 



CO(NH 2 ) 2 + 3NaBrO = 3NaBr + C0 2 + N 2 



An excess of caustic soda is used in the reaction to absorb 
the carbon dioxide, the nitrogen, being left free, is collected 
and measured. Since one gram of urea furnishes 370 c.c. of 
nitrogen at o° C, 760 mm. 
pressure, the quantity of urea 
may be calculated from the vol- 
ume of the nitrogen evolved. 

The solutions for making 
this test should be freshly 
made, as follows : A solution of 
caustic soda is kept for use 
containing 100 grams sodium 
hydroxide dissolved in 250 c.c. 
of water. Bromine is kept in a 
separate bottle. When it is de- 
sired to make the test, 10 c.c. 
of caustic soda solution are 
mixed with 1 c.c. of bromine, 
and the mixture is then diluted 
with an equal volume of water. 

The test is made with the aid 
of the Doremus Ureometer, 
as shown in the cut. The 
above mixture is introduced 
into the main tube of this in- 
strument and 1 c.c. of urine is 
allowed to flow into the liquid 
from the side tube in small por- 
tions at a time by turning a stopcock. As nitrogen gas is 
disengaged, it rises in the tube of the instrument, displacing the 
liquid and the volume may be read off from a graduated scale. 




Hinds-Doremus Ureometer. 
(Holland.) 



420 



TEXT-BOOK OF CHEMISTRY 



The instrument is usually graduated to represent fractions 
of a gm. of urea to the cubic centimeter of urine, ranging from 
o.oi to 0.03 gm. The percentage of urea may be expressed 
from this reading by removing the decimal point two figures 
to the right, thus : 0.0 1 gm. is 1 per cent, of urea. 

Uric Acid, H 2 C 5 H 2 N 4 3 . Uric acid occurs in the urine in 
combination chiefly, as the urates of sodium:, potassium, ammo- 
nium, and to a less extent in combination with calcium and 
magnesium. Its exact source and manner of formation are not 
known at the present time, but it is believed to be derived from 



Fig. 51. 




Uric Acid Crystals, a, rhombic forms ; b, barrel form ; c, 
rosettes. (Bartley's Clinical Chemistry.) 



sheaves 



the nucleins of nucleo-proteids, and to be formed in the spleen. 
Uric acid, when pure, is a white, crystalline solid. It crys- 
tallizes from the urine in yellowish-red crystals, of prismatic 
shape. It is odorless and tasteless ; soluble in 16,000 parts of 
cold water, or 1,600 parts of boiling water; insoluble in alco- 
hol or ether. On account of its great insolubility it frequently 



PHYSIOLOGICAL CHEMISTRY - 42 1 

separates from solution in the body, forming deposits in the 
tissues and urinary tract. 

Uric acid may be prepared as follows : Add 100 c.c. hydro- 
chloric acid to 1,000 c.c. of urine, allow to stand for 24 hours, 
collect the crystals on a filter, wash with water, transfer to a 
beaker and dissolve in caustic soda solution. The solution is 
decolorized with bone black, hydrochloric acid is added to re- 
precipitate the urea, and the purified crystals, so obtained, are 
collected, washed and dried. 

The normal daily quantity of uric acid varies from 0.2 to 
1.2 gram. 

Uric acid is increased in excessive nucleo-proteid diet and 
insufficient exercise; in many acute diseases, especially of the 
lungs ; in organic heart disease ; in diseases of the liver or 
spleen ; in anemia, gout and diabetes mellitus. It is diminished 
by a vegetable diet; after continued ingestion of large quanti- 
ties of water ; in most of the chronic diseases, and after large 
doses of quinine. 

Detection of Uric Acid. 1. Murexide Test. To a few 
fragments of uric acid in a porcelain dish add a drop of nitric 
acid and evaporate. Add a drop of ammonia water to the dry 
residue, when a purplish-red color will make its appearance. 

2. Add magnesia mixture to the urine and then a solution 
of silver nitrate; uric acid deposits as a gelatinous precipitate. 

3. Uric acid or urate boiled with Fehling's solution gives a 
yellowish or reddish precipitate, resembling the precipitate 
formed by glucose. 

Estimation of Uric Acid. Heintz's Method. To 200 c.c. 
of filtered urine add 10 c.c. strong hydrochloric acid and let 
stand in a cool place for 24 hours. Collect the crystals on a 
previously dried and weighed filter-paper, wash with cold water, 
dry at 100 C. and weigh. By deducting the weight of the 
filter-paper, the quantity of uric acid in 200 c.c. of urine will 



422 



TEXT-BOOK OF CHEMISTRY 



be obtained. This method only gives approximate results, but 
it is sufficiently accurate for clinical purposes. 

Hippuric Acid, C 9 H 9 N0 3 , is present in large amount in 
the urine of herbivorous animals. It is present in small quan- 
tities in normal human urine, the daily quantity being 0.5 to 1.0 
gram. It is increased by a vegetable diet, in diabetes, in acute 
febrile diseases and chorea, but it has no special clinical sig- 
nificance. 

Hippuric acid may be detected by evaporating a portion of 
the urine to dryness with a little nitric acid, and heating the dry 
residue in a test-tube. The odor of bitter almonds is observed 
if the acid is present. 

Oxalic Acid is excreted in small amount in the urine, 
about 0.1 gm. daily, chiefly as calcium oxalate. When it occurs 
in excess, indicating deficient oxidation, it frequently forms 
octahedral or dumb-bell crystals upon standing. 



Fig. 52. 



Fig. 53. 





Calcium Oxalate Crystals, a, 
octahedra ; b, basal plane 
of an octahedron ; c, com- 
pound forms ; d, dumb- 
bells. (Bartley's Clinical 
Chemistry.) 



Dumb-bell Crystals of 
Oxalate of Cal- 



cium. 

Clinical 

try,) 



(Bartley's 
Chemis- 



The elimination of oxalic acid is increased by a diet of to- 
matoes, beets, spinach, etc., and in diabetes and jaundice. 

Indican, indoxyl-potassium sulphate, C 8 H 6 NOS0 2 OK. 
This compound is formed from indoxyl, which is produced by 
intestinal fermentation and putrefaction. It occurs normally in 



PHYSIOLOGICAL CHEMISTRY p 423 

the urine to the extent of .002 per cent. It is increased by in- 
creased fermentation and putrefaction in the intestine. 

Tests for Indican. 1. Equal volumes of urine and hydro- 
chloric acid with a few drops of nitric acid are boiled together, 
cooled and agitated with chloroform. Upon standing, the 
chloroform separates as a violet-colored liquid, having dis- 
solved the indican. 

2. To five c.c. of hydrochloric acid in a flask, add 20 drops 
of urine with agitation ; the color will be light yellow if the 
proportions of indican be normal ; if in excess, the color will 
be violet or blue. Absence of color indicates absence of indican, 
though a coloration may appear later on without significance. 

Other organic bodies are found in urine, such as creatinin, 
allantoin, mucin, coloring matters, etc., the determination of 
which is only a matter of scientific interest. 

Abnormal Constituents. 

The abnormal constituents of urine are proteids, carbohy- 
drates, bile products, constituents of blood, acetone and diacetic 
acid. 

Albumin. The proteids usually found in the urine are 
serum-albumin and serum-globulin, but albumoses, peptones, 
nucleo-albumins and hemoglobin sometimes occur. 

Since the tests for albumin are dependent upon its coagula- 
tion and precipitation, the urine should be clear when these 
tests are applied. If the urine be cloudy, filtration will generally 
serve to remove the turbidity. Sometimes the urine contains 
a precipitate of the amorphous earthy phosphates ; in order to 
remove these, a little magnesium oxide may be rubbed with 
the urine and the liquid subjected to filtration. Turbidity due 
to the presence of urates will disappear upon warming. 

Tests for Albumin. 1. Heat Test. Add one or two drops 
of 10 per cent, acetic acid, to a test-tube half filled with urine. 



424 TEXT-BOOK OF CHEMISTRY 

If the urine be alkaline add sufficient acid to produce an acid 
reaction. Heat the upper part of the urine to the boiling point 
and if albumin be present it will be indicated by the appear- 
ance of a white precipitate. A precipitate is sometimes caused 
by the presence of earthy phosphates, but these quickly dis- 
solve upon the addition of a few drops of acetic acid, which 
causes an increased precipitation of albumin. 

If one-fourth volume of a saturated solution of sodium 
chloride be added to the urine before applying this test, the 
precipitation of globulin is aided, and mucin is kept in solution. 

A precipitate caused by the addition of acetic acid is due to 
the presence of mucin or nucleo-albumin, and should be re- 
moved by filtration. 

2. Nitric Acid Test. About half an inch of pure nitric acid 
is placed in a test-tube and the urine is poured down the side 
of the tube so as to form a separate layer upon the acid. If 
albumin be present a white band, or zone, makes its appearance 
at the line of contact of the two liquids. 

The presence of urates in a concentrated urine sometimes 
gives rise to the formation of a white zone resembling albumin. 
The white zone from urates is not sharply defined like that 
from albumin, but it is diffused into the surrounding urine ; the 
precipitate of urates will disappear upon warming, but albumin 
remains permanent. 

3. F err cyanide Test. A mixture consisting of 1 part of 50 
per cent, acetic acid, and 2 parts 10 per cent, ferrocyanide solu- 
tion is placed in a test-tube, and urine is carefully poured down 
the side of the test-tube so as to form a separate layer. If 
albumin be present, a white zone makes its appearance at the 
line of contact of the two liquids. This zone may be caused 
by the presence of urate, but in such a case it disappears upon 
heating. 

4. Roberts' Contact test is made like the above, using a solu- 



PHYSIOLOGICAL CHEMISTRY 



425 



Fig. 54. 



tion of 1 part strong nitric acid and 5 parts saturated solution 
magnesium sulphate. Albumin is indicated by the appearance 
of a white band at the line of contact of the two liquids. Alka- 
loids, resins and albumoses give the white 
zone, it disappears upon warming when 
caused by these bodies, and may thus be dis- 
tinguished from albumin. 

This test is said to be sufficiently delicate to 
detect 1 part in 50,000 or less. 

Estimation of Albumin. For the approxi- 
mate estimation of albumin Esbach's albumi- 
nometer is used. This is a graduated test- 
tube, which is filled with urine to the mark 
" U," and with reagent to " R " ; the mixture 
is shaken and allowed to stand for 24 hours 
when the amount of albumin, in grams per 
liter, is read off on the graduated scale. The 
standard solution consists of 10 gm. picric 
acid, 20 gm. citric acid, dissolved in distilled 
water to make a liter. 

The Gravimetric Method consists of acidi- 
fying 100 c.c. of urine with acetic acid and 
precipitating the albumin by heat. The pre- 
cipitate is filtered out, dried and weighed. 

Blood. Presence of blood in the urine gen- 
erally imparts a red, or brownish color, or a 
smoky appearance. The presence of 1 part 
in 1,500 is said to give a smoky urine, and 1 
part in 500, a bright red or chocolate-brown, Esbach's Albu- 
depending upon the degree of decomposition menometer. 
of the blood. The entire blood or simply 
hemoglobin may be present. 

Blood in the urine may be recognized by use of the micro- 
scope by the appearance of normal or altered corpuscles ; it may 



1 



% 



426 TEXT-BOOK OF CHEMISTRY 

also be recognized by chemical tests, which are of special value 
when the blood has undergone disintegration. 

Tests. I. Add a few drops of ozonized ether to a few c.c. 
of tincture of guaiac in a test-tube and then add the suspected 
urine, so as to form a separate layer at the bottom of the test- 
tube. If hemoglobin be present, a blue ring will make its 
appearance at the line of contact of the two liquids, which does 
not disappear on heating. 

2. Make the urine alkaline with caustic soda and boil; the 
precipitate of phosphates is colored red if coloring matter of 
blood be present. Collect the precipitate on a filter, wash and 
dissolve in acetic acid ; the solution becomes red if blood pig- 
ment be present, and by exposure to air the color gradually 
disappears. 

Pus. Pus in the urine gives a cloudy appearance, and forms 
a grayish-white deposit upon standing. Pus may be recognized 
by examining the sediment under the microscope, when pus 
corpuscles will be seen having the same appearance as leuco- 
cytes. A drop of 20 per cent, acetic acid passed under the 
slide will cause the granules of the corpuscles to dissolve, the 
nucleus to< become more distinct and the cell to> swell. 

A chemical test for pus is to add to the urinary deposit, after 
decantation of the urine, a few cubic centimeters of caustic 
potash solution. If pus be present, a thick, tenacious, viscid 
mass is formed, which adheres to the sides of the vessel and 
can be drawn out into strings when a glass rod is dipped into 
the mass. 

Sugar. Glucose, C 6 H 12 6 , is the form of sugar usually 
found in urine. It is said to be present in normal urine to the 
extent of .01 per cent. It is present in large quantities in dia- 
betes mellitus, sometimes as much as 10 per cent., but more 
frequently the percentage in this disease varies from 3 to 5. 
The presence of sugar is sometimes indicated by a high specific 



PHYSIOLOGICAL CHEMISTRY \2J 

gravity, 1.030 to 1.050, but increased secretion of fluids may 
give a low specific gravity to a urine containing sugar the daily 
quantity of which may be very considerable. 

As has been explained in the preceding pages, many of the 
tests for glucose depend upon its reducing action upon certain 
metallic oxides in the presence of alkalies. In applying these 
tests, a precipitate of earthy phosphates is sometimes produced, 
which might be mistaken for sugar. For this reason, it is well 
to remove these phosphates before testing for sugar, by adding 
a few drops of potassium hydroxide solution and filtering out 
the precipitated earthy phosphates. 

Before applying the tests for sugar, albumin should be tested 
for, and should be removed from the urine, if present. 

Tests. 1. Haines' Test. Make a solution by dissolving 30 
grains of pure cupric sulphate in one-half an ounce of distilled 
water; add one-half ounce of pure glycerine, mix, and add 5 
ounces of liquor potassa. 

The test is applied by gently boiling about 1 dram of the solu- 
tion in a test-tube and adding 6 or 8 drops of the suspected 
urine. A copious yellow, or yellowish-red, precipitate forms 
if sugar be present. 

2. Fehling's Test. Make two solutions, according to the fol- 
lowing formulae: 

Crystallized cupric sulphate 34.64 gm. 

Water to make 500.00 c.c. 

Pure crystallized potassium sodium tartrate 173.00 gm. 

Potassium hydroxide 125.00 gm. 

Water to make 500.00 c.c. 

These solutions are to be kept in separate bottles and equal 
volumes of the two are to be mixed at the time they are to be 
used. The mixed solution serves as a qualitative and also as 
a quantitative test. 

When the solution is boiled, and urine added in small por- 



428 



TEXT-BOOK OF CHEMISTRY 



tions at a time, after removal from the flame, sugar is indi- 
cated by a yellow, or yellowish-red, precipitate. 

3. Boettger's Test. Add an equal volume of liquid potassa, 
and a little subnitrate of bismuth, to the urine and boil. If 
sugar be present, a gray or black color is produced. Presence 

Fig. 55. 




Crystals of Phenyl-glucosazone. 

of sulphur gives the same reaction, and consequently, the test 
is of no value in albuminous urine. 

4. Fermentation Test. See glucose. 

5. Phenyl Hydrazine Test. Boil 8 c.c. of the urine with 1 
gm. sodium acetate and .5 gm. phenyl-hydrazine. A yellow or 
orange color makes its appearance in presence of sugar. Allow 
to cool and add acetic acid; a yellow precipitate of phenyl- 
glucosazone makes its appearance in needle-shaped crystals. 

6. Quantitative Estimation. Place 10 c.c. of Fehling's solu- 
tion in a 200-c.c. flask, add 40 c.c. distilled water and place on 



PHYSIOLOGICAL CHEMISTRY 



429 



Fig. 56. 



wire gauze over the Bunsen burner. Take the specific gravity 

of the urine and, if over 1.030, dilute to 1 in 10 of distilled 

water (1 part urine and 9 parts distilled water) ; if the specific 

gravity is less than 1.030, 

dilute to 1 in 5 (1 part urine 

and 4 parts water). Place 

the diluted urine in a buret 

over the flask. Bring the 

Fehling's solution to a boil 

and add the urine, drop by 

drop, until the blue color of 

the former has disappeared 

from the meniscus. 

Since 10 c.c. of Fehling's 
solution will be decomposed 
by -05 gm. of glucose, the 
quantity of sugar present 
may be easily calculated 
from the number of cubic 
centimeters of urine used 
in the titration. 

Bile. The color of urine 
containing bile is usually 
yellow, greenish-yellow or 
brown. When such urine 
is shaken, the froth is quite 
permanent, and is yellow in 
color. Filter-paper or linen 
is permanently stained by 
the urine. 




Titration in Fehling's Test. 



The reactions for bile depend upon the presence of biliary 
acids and biliary coloring matters. 

Gmeliris Test for Bile Pigments. Place a small quantity of 



43° TEXT-BOOK OF CHEMISTRY 

old, yellow nitric acid in the bottom of a test-tube and float 
some of the suspected urine on its surface. The presence of 
bile pigment is shown by a play of colors at the line of contact, 
beginning with green and passing to blue, violet, red and 
yellow. 

Another way to apply the same test is to mix a strong solu- 
tion of sodium nitrate with the urine and pour this upon the 
surface of strong sulphuric acid in a test-tube. In the presence 
of bile pigments, the colors make their appearance, as above. 

Still another modification is to 1 place a few drops of urine 
on a porcelain plate, and bring a few drops of nitric acid, to 
which have been added a drop of sulphuric acid, near to the 
urine, so that the two liquids will gradually coalesce. The same 
play of colors appears if bile be present. 

Pettenkofer's Test for Bile Acids consists in dissolving a few 
grains of cane sugar in a small quantity of urine in a test-tube, 
allowing strong sulphuric acid to flow down the side of the 
test-tube so as to form a separate layer at the bottom. Presence 
of bile acids is indicated by appearance of a purple band at 
upper surface of the acid. Upon shaking this mixture the 
liquid becomes turbid, then clear, and it turns yellow, red and 
finally purple-violet. 

Diazo-reaction is obtained in the urine of patients with 
typhoid fever, measles, sepsis and tuberculosis. Two solutions 
are necessary and should be kept in the dark: a. Dissolve 2 
gm. sulphanilic acid in 50 c.c. hydrochloric acid and 1,000 c.c. 
of water, b. Make a .5 per cent, solution of sodium nitrite. 

To apply the test, add 1 c.c. of sodium nitrite solution to 50 
c.c. of sulphanilic acid solution ; to the mixture add an equal 
volume of urine and shake. Add ammonia water, carefully, 
so as to form a separate layer on the surface. A positive re- 
action gives a crimson zone at the line of contact and, when 
shaken, the liquid is crimson and the froth pink. 






PHYSIOLOGICAL CHEMISTRY 43 I 

Acetone is recognized by acidifying 500 ex. of the urine 
with acetic acid and distilling. A few drops of iodine solu- 
tion ( 1 part iodine, 2 parts potassium iodide, dissolved in water 
to make 10 parts) and of potassium hydroxide are added to 
the distillate. Iodoform is precipitated if acetone is present. 

Legal' 's Test. To one fourth of a test-tube of urine add a 
few drops of fresh, strong solution of sodium nitroprusside, 
and a few drops of acetic acid to prevent reaction with crea- 
tinin. The mixture is then made alkaline with caustic soda, 
and, if acetone be present, a red color makes its appearance, 
which increases to purple-red. 

Diacetic acid may be recognized by adding a few drops of 
ferric chloride to the urine, filtering off the precipitate and 
adding more of the ferric chloride to the filtered liquid. A 
deep red color is produced if diacetic acid is present. The color 
disappears upon boiling. 

The same test should be applied to an ethereal extract made 
by shaking urine, which has been acidified with a few drops 
of sulphuric acid, with ether. The same reaction is obtained 
as above if diacetic acid is present. Phenol, antipyrine, salicylic 
acid or thalline give the same color with ferric chloride, but it 
does not disappear upon boiling. 

Urinary Concretions. 
Urinary calculi may be found in almost any part of the 
genito-urinary tract, but they occur most frequently in the 
renal tubules, renal pelvis or urinary bladder. In structure they 
may be either homogeneous or made up of concentric layers de- 
posited around a central nucleus. The nucleus may be a for- 
eign body, a small concretion formed high up in the urinary 
tract, or a clot of blood or fibrin, around which, under favor- 
able conditions, normal or abnormal constituents of the urine 
are deposited. These conditions are: Concentration, hyper- 
acid reaction, alkaline reaction, or the presence of an excess of 



43 2 TEXT-BOOK OF CHEMISTRY 

substances not freely soluble. A combination of two or more- 
of these conditions is usually active in the formation of calculi. 
Urinary calculi are named from their principal constituent, e. g.,. 
uric acid, calcium oxalate, etc. In point of frequency of ap- 
pearance two thirds to three fourths are chiefly composed of 
uric acid or urates ; next in order, phosphates, oxalates and 
carbonates. Among substances rarely forming the chief con- 
stituent of a calculus are cystin, xanthin, urostealith, fibrin and 
indigo. 

Pure urostealith, xanthin and cystin calculi have been re- 
ported; fibrin occurs principally as a nucleus; indigo may be 
present in such quantities as to impart to the stone its charac- 
teristic color. 

In making an analysis of a calculus it must be sawed dia- 
metrically through. If homogeneous, the sawdust may be 
used for chemical analysis; if it is composed of concentric 
layers, a powder must be obtained from each layer by scraping 
with a knife. The chemical analysis is conducted as follows : 

Heat some of the powder on platinum foil and note which of the fol- 
lowing phenomena occurs : 

A. Complete combustion by charring without ignition. 

B. No change, or reduction to incombustible residue. 

C. Complete combustion by ignition. 
In case " A " the indications are : 

Uric acid, 
Ammonium urate, 
Xanthin. 
To differentiate : 

Original powder + HN0 3 ; evaporate + NH 4 OH = purple color = 

Uric acid or ammonium urate. 
Original powder + KOH; heat = odor of NH 3 = Ammonium 

urate. 
Original powder -f- HN0 3 ; evaporate -f KOH = pink color ; heat — - 
violet color = Xanthin. 
In case " B " the indications are : 
Sodium urate, 
Calcium oxalate, 






PHYSIOLOGICAL CHEMISTRY 



433 



Calcium carbonate, 

Calcium phosphate, 

Ammonium magnesium phosphate. 
To differentiate : 

Residue soluble in H 2 0, alkaline reaction. Original powder + 
HNOs, evaporate + NH 4 OH = purple color = Sodium urate. 

Residue soluble in acetic acid with effervescence. Original powder 
insoluble in acetic acid = Calcium oxalate. 

Residue slightly soluble in H 2 with alkaline reaction. Original 
powder soluble in acetic acid with effervescence = Calcium 
carbonate. 

Original powder -f- KOH, heat = odor of NH 3 . Original powder 
soluble in acetic acid without effervescence = Ammonium mag- 
nesium phosphate. 

Original powder + KOH, heat, does not give odor of NH 3 . Orig- 
inal powder soluble in acetic acid without effervescence = Cal- 
cium phosphate. 
In case " C " the indications are : 

Urostealith, 

Fibrin, 

Cystin. 
To differentiate : 

Yellow flame, resinous odor = Urostealith. 

Yellow flame, odor of burnt hair = Fibrin or blood clot. 

Blue flame, pungent odor of S0 2 = Cystin. 

Urinary Sediments. 

To obtain urinary sediment for examination one of two 
methods may be adopted : ( 1 ) The centrifugal method, by 
which the urine in conical tubes is revolved 2,000 times per 
minute, usually requires only 5 minutes for complete sedi- 
mentation. (2) The gravity method, by which the urine in a 
conical sedimentation glass is allowed to stand in a cool place, 
and requires about 24 hours for complete sedimentation. 

Urinary sediments may be divided into two distinct classes : 

(1) The chemical sediments, which are the products of normal 
or abnormal chemical processes in various parts of the body; 

(2) The histological sediments, which are the products of nor- 
mal and abnormal tissue changes in definite parts of the genito- 
urinary tract. 

29 



434 text-book of chemistry 

The Chemical Sediments. 

For the examination of the chemical sediment it is much 
better to adopt the centrifugal method, as the rapidity with 
which sedimentation takes place does not allow time for the 
occurrence of putrefactive changes in the urine with conse- 
quent precipitation of secondary crystals or amorphous salts. 

To facilitate the differentiation of the chemical urinary sedi- 
ments, they may be classified according to the reaction of the 
urine in which they are usually precipitated, those occurring 
in acid urines, and those occurring in alkaline urines. 

i. The most common sediments found in acid urines are uric 
acid, sodium urate, and calcium oxalate. The rarer sediments 
are cystin, creatinin, hippuric acid, leucin and tyrosin. 

2. The most common sediments found in alkaline urine are 
ammonio-magnesium phosphate, calcium phosphate, and ammo- 
nium urate. Calcium carbonate may occur as a rare sediment 
in this class. The following is a brief description of the chief 
differential characteristics, chemical and microscopical, of the 
members of these two classes : 

Uric Acid. Usually large, yellow (rarely colorless) rhom- 
boidal prisms or lozenges with rounded or pointed ends, occur- 
ring singly or attached in multiple groups, feebly soluble in 
hot H 2 0, readily soluble in KOH solution, insoluble in HC1, 
acetic acid or alcohol. 

Sodium urate. As a rule, amorphous granules in mass-like 
aggregations, less frequently colorless, needle-like prisms in 
stellate or sheaf-like groups readily soluble in hot H 2 0, and 
KOH solution, in HC1 and acetic acid with subsequent forma- 
tion of uric acid crystals. 

Calcium oxalate. As a rule, small colorless, highly refrac- 
tive crystals, consisting of two four-sided pyramids, base to 
base, usually seen vertically, and resemble the back of a square 
envelope — lines crossing diagonally from corner to corner, 



PHYSIOLOGICAL CHEMISTRY 
Fig- 57. 



435 



d — 




a, Fungus ; b, amorphous sodium urate ; c, uric acid ; d, calcium oxalate. 
(Bartley's Clinical Chemistry.) 

crossing in center, less frequently form highly refractive dumb- 
bell or oval crystals. Insoluble in acetic acid; feebly soluble 
in KOH solution; soluble in HC1. 

Fig. 58. 




A, Crystals of cystin ; B, oxalate of lime ; c, hour-glass forms. (Bartley's 
Clinical Chemistry.) 



436 



TEXT-BOOK OF CHEMISTRY 



Cystin. Thin, colorless hexagonal plates, usually larger than 
crystals of calcium oxalate. Insoluble in acetic acid ; soluble in 
HC1 ; readily soluble in KOH solution. 

Creatinin. Colorless prisms or plates, either lozenge or bar- 
rel-shaped, sometimes resembling colorless uric acid crystals, 
but readily soluble in hot H 2 0, or alcohol. 

Hippuric Acid. Large, colorless plates or prisms, occurring 
singly or conglomerate, sometimes resembling ammonio-mag- 
nesium-phosphate crystals, but are differentiated by being 

soluble in acetic acid. 

Fig. 59. 




Hippuric Acid. (Bartley's Clinical Chemistry.) 



Leucin. Yellow or brown globules, sometimes showing fine 
radiating striations. 

Tyrosin, Exceedingly fine colorless needles, in sheaf-like 
aggregation. 

Leucin and tyrosin usually occur together. Both are readily 
soluble in hot H 2 0, HC1, acetic acid, and KOH solution, and 
sparingly soluble in alcohol. 



PHYSIOLOGICAL CHEMISTRY 



437 



Ammonio-M ague slum Phosphate. In distinctly alkaline 
urine, always colorless, highly refractive, rhomboidal crystal 
or plates, or three-sided prisms. The rhomboids are bevelled at 
the sides and ends, the " coffin-lid crystal." In neutral urine, 
occurs in very irregular plates or partially symmetrical feathery 
crystals. 

Calcium Phosphate. Usually highly refractive amorphous 
granules either evenly scattered or in clusters but distinctly un- 

Fig. 60. 




a,a, Leucin balls ; b,b, tyrosin sheaves ; c, double balls of ammonium urate. 
(Bartley's Clinical Chemistry.) 

like amorphous sodium urate. Sometimes in slender, colorless 
rods or very narrow, pointed needle-like pyramids, which are 
frequently arranged in a radial manner, their points directed 
to a common center. 

All phosphates are readily soluble in acetic acid without 
effervescence, which easily distinguishes them from crystals 
for which they might be mistaken. 

Ammonium Urate. Brown globules, varying in shape and 



43 8 



TEXT-BOOK OF CHEMISTRY 



size, usually with distinct concentric structure and frequently 
with radial striation ; sometimes with smooth surfaces ; perhaps 
more frequently provided with multiple, curved, thorny pro- 
jections ; soluble in hot H 2 0, soluble in KOH solution, soluble 
in HC1, and acetic acid, with subsequent formation of uric 
acid crystals. 

Fig. 6i. 




a, Acid ammonium urate ; b, ammonia-magnesium phosphate ; c, bacteria. 
(Bartley's Clinical Chemistry.) 



Calcium Carbonate. Small colorless, highly refractive gran- 
ules of irregular shape ; rarely, in combination with magnesium 
forming small, narrow highly refractive rhomboidal or trape- 
zoidal crystals ; soluble in acetic acid with effervescence. 

Besides the foregoing chemical sediments, there are some 
which can not be classified according to the reaction of the 
urine in which they are usually precipitated ; these are, Choles- 
terin, Hematoidin, and Melanin. 

Cholesterm occurs in large, thin, irregular, quadrilateral 
plates frequently broken at the corners, insoluble in water, 
dilute acids or alkalies soluble in ether and chloroform ; colored 
violet-red with iodine solution. 



PHYSIOLOGICAL CHEMISTRY 439 

Hematoidin. Occurs either in small needle-like crystals or 
minute rhombic plates or scales, varying in color from orange- 
red to brown; soluble in KOH solution, and acquire a green 
rim on the addition of HN0 3 . 

Melanin occurs in small black granules, insoluble in water, 
ether or dilute acid; soluble in NH 4 OH, which latter distin- 
guishes it from precipitated carbon. 



440 



TEXT-BOOK OF CHEMISTRY 



The Histological Sediments. 
i. These consist of mucous corpuscles, pus corpuscles, epi- 
thelial cells, and blood corpuscles, the appearance of which is 
shown in the following cuts : 



Fig. 62. 




Mucous Threads and Corpuscles (X 500). (After Heitzmann.) 



PHYSIOLOGICAL CHEMISTRY 
Fig. 63. 



441 





& 1(6^ />55s. P^» ^*^ ^^ 




Pus-corpuscles (X 500). F, pus-corpuscles with fat-globules; C, ciliated 
pus-corpuscles ; H, pus-corpuscles with hematoidin crystals. (Heitzmann.) 




.a, Epithelial cells from male urethra ; &, from vagina ; c, from prostate ; 
d, Cowper's glands ; e, Littre's glands ; f, female urethra ; g, bladder. 
(Bartley's Clinical Chemistry.) 



442 



TEXT-BOOK OF CHEMISTRY 
Fig. 65. 




Colored and Colorless Blood-corpuscles. (Holland.) 
Fig. 66. 




Crenated Red Blood-corpuscles in Urine. (Holland.) 



PHYSIOLOGICAL CHEMISTRY 



443 



2. Casts are moulds of the uriniferous tubules, consisting of 
fibrin. The chief varieties of casts are as follows: Hyaline 
casts, which are clear and transparent ; blood casts, in which 
blood corpuscles are imbedded in the fibrinous mould ; epi- 
thelial casts, containing epithelial cells on the surface ; granular 



Fig. 67. 




Hyaline Casts (X 500). (Heitzmann.) C, casts from convoluted tubules: 
N, from narrow tubules ; S, from straight connecting tubules. 



444 



TEXT-BOOK OF CHEMISTRY 



casts, having a granular appearance ; fatty casts, containing oil 
drops on the surface ; waxy casts, more dense than hyaline casts. 
The appearance of the different casts under the microscope is 
shown in the following cuts : 




Blood Casts (X 500). (Heitzmann.) C, casts from convoluted tubules 
N ', from narrow tubules ; S, from straight collecting tubules. 



PHYSIOLOGICAL CHEMISTRY 



445 



Fig. 69. 




Epithelial Casts (X 500). (Heitzmann.) C, casts from convoluted tubules 
N, from narrow tubules ; S } from straight collecting tubules. 



446 



TEXT-BOOK OF CHEMISTRY 



Fig. 70. 




Granular Casts (X 500). (Heitzmann.) C, from convoluted tubules; N, 
narrow tubules ; 5", straight collecting tubules. 



PHYSIOLOGICAL CHEMISTRY 



447 



Fig. 71. 




Fatty Casts (X500). (Heitzmann.) C, from convoluted tubules; A r , 
narrow tubules; S, straight collecting tubules. 



448 



TEXT-BOOK OF CHEMISTRY 



Fig. 72. 




Waxy Casts (X500). (Heitzmann.) C, from convoluted tubules; N, 
narrow tubules ; S, straight collecting tubules. 



INDEX. 



A. 

Abnormal constituents of urine. 423 

Absolute Zero 29 

Absorption spectra 43 

Acacia 310 

Acetanilide 342 

Acetate of ammonium 286 

copper 287 

ethyl 297 

iron 286 

lead 287 

manganese, potassium and 

zinc 286 

Acetone 282 

Acetone in urine 430 

Acetone, test for 431 

Acetylene 269 

Acetylene series 269 

Acid, or bi-salt 84 

Acid, acetic 285 

amido acetic 318 

amido formic 318 

arsenous 226 

arsenic 22^ 

benzoic 335 

boric 116 

butyric 287 

carbolic 333 

carbonic 114 

cathartic 315 

caproic 288 

caprilic 288 

chloric 139 

citric 292 

chromic 200 

cyanic 324 

definition of 83 

formic 285 

gallic 337 

glycocholic 403 

glycollic 289 

hippuric 422 

hydriodic 144 

hydrobromic 141 

hydrochloric 136 

hydrocyanic 321 

30 



Acid, hydrofluoric 148 

hydrosulphuric 119 

hypochlorous 138 

hyponitrous 106 

hypophosphorous 130 

lactic 290 

lauric 288 

linoleic . 289 

malic 291 

manganic 197 

margaric 288 

meconic 353 

metaphosphoric 133 

myronic 315 

myristic 288 

nitric 106, 107, 108 

nitrohydrochloric 138 

nitrous 106 

oleic 288 

oxalic 290-422 

oxybenzoic 336 

palmitic 288 

pelargonic 288 

phosphate of calcium 177 

phosphoric 132 

phosphorous 131 

phenol 336 

phenol sulphonic 334 

phthalic 334 

perchloric . .• 139 

permanganic 197 

pyrogallic 384 

pyrophosphoric 133 

pyrosulphuric 124 

salicylic 336 

sozalic 334 

stearic 288 

sulphanilic 342 

sulphuric 122 

sulphurous 121 

sulphocarbolic 334 

sulphocyanic 324 

tannic 338 

tartaric 291 

taurocholic 403 

thiosulphuric 125 

449 



450 



INDEX 



Acid, trioxybenzoic 337 

uric 420 

detection of 421 

estimation of 421 

valerianic 287 

Acids, organic 258 

Aconitine 356 

Actinic rays 50 

Action, catalytic 81 

Action of magnet on electric 

current 55 

Adhesion 8 

Adonin 315 

Air-pump, Sprengel's 22 

Air-pump, the 21 

Albumins 367 

Albuminates 368 

Albumin 423 

estimation of 425 

ferrocyanide test for 424 

heat test for 423 

nitric acid test for 424 

Roberts' test for 424 

Alcohol, amyl, propyl, butyl... 2^j 

beverages 2Tj 

ethyl 275 

methyl 274 

tests 2TJ 

Alcohols 258-273 

sulphur derivatives 281 

Aldehyde, acetic 280 

formic 279 

methyl 279 

Aldehydes 258-278 

Alkali metals 151 

analytical reactions for 
168 

Alkaline earth metals 173 

Alkaloids 259-350 

genl. method of prepara- 
tion 351 

liquid volatile 352 

poisoning by 352 

properties 351 

solid non-volatile 352 

tests and precipitants .... 351 

Allotropic modification 86 

Alloys 149 

Allyl isosulphocyanate 324 

Aluminum 184 

chloride 184 

hydroxide 185 

oxide 185 



Aluminum silicates 187 

sulphate 186 

Alums 186 

Alum 186 

dried 187 

Ammonia 102 

water 104 

liniment 300 

Ammonio-copper compounds... 210 

Ammonium 164 

bromide 165 

carbonate 165 

chloride 165 

hydrogen sulphide 167 

iodide 165 

phosphate 167 

sodium hydrogen phosphate 167 
Ammonium sulphate, nitrate 

and nitrite 167 

Ampere, the 60 

Amygdalin 315 

Amylene 268 

Amyl nitrite 298 

Amylum 307 

Amides 317 

Amido acids 318 

acetic acid 318 

formic acid 318 

derivatives of benzene.... 340 

Amines 317 

Analytical table 239-82 

Analysis, calculation of results. 376 

gravimetric method 371 

quantitative 371 

of stomach contents 397 

volumetric 374 

Anhydride 98 

Anhydrous body 98 

Animal food 383 

Aniline 341 

para-sulphonic acid 342 

Anode 54 

Anodyne, Hoffmann's 297 

Antifebrine 342 

Antimonic oxide 233 

Antimonous oxide 233 

Anthracene 346 

Antimony 232 

acids 233 

chloride 232 

hydride 232 

sulphides 233 

sulphurated 234 



INDEX 



451 



Antimony pentasulphide 234 

tests for 234 

and potassium tartrate.... 292 

Antipyrine 344 

Antitoxines 363 

Apomorphine 353 

Apothecaries' weight 14 

Arbutin 3 1 5 

Archemides, theory of 17 

Argentum 2I 4 

Argon 101 

Arithmetic, chemical 74~75 

Aromatic hydrocarbons 326 

Arsenic 224 

acid 227 

hydride 225 

oxide 227 

sulphide 228 

tri-chloride 225 

tri-oxide 225 

tests for 228 

Arsenous acid 226 

oxide 226 

Atmosphere, the 101 

Atmospheric pressure 21 

Atomicity or valence 71-72 

Atomic theory, the 67 

weight 70 

and gas volume 7 1 

Atoms &7 

Attraction, capillary 9 

Atropine 356 

Aurum 235 

Avogadro, law of 69 

Axis, optical 46 

Azo-compounds 259 

Azo- and diazo-compounds. . . . 343 



B. 

Balance, the 12-13 

Balsams 331 

Barium 179 

chloride 180 

dioxide 180 

hydroxide 180 

oxide 180 

toxicology of 181 

Barometer 20 

Base, definition of 83 

Basic salt 84 

Battery, electric 53 

Beet-sugar 305 



Benzene 329 

amido derivatives 340 

dimethyl 330 

nitro derivatives of 338 

Benzaldehyde 334 

Benzoic acid 335 

Benzol 329 

Beryllium 173 

Berthollet, laws of 81 

Bettendorf's test 228 

Bichromate of potassium 200 

Bile 402 

Bile in the urine 429 

test for 429 

pigments ; 402 

Bismuth 211 

and ammonium citrate.... 294 

citrate 294 

subcarbonate 213 

subiodide 212 

subnitrate 212 

tests for 213 

trichloride 212 

Bisulphide of carbon 120 

Bitartrate of potassium 292 

Bitter principles, definition. . . . 260 

Biuret reaction 366 

Bleaching powder 177 

Blood, the 387 

corpuscles 389 

in the urine 425 

plaques 392 

plasma 389 

Boettger's test 312-428 

Boiling 35-36 

Bone 393 

ash , 177 

black 177 

Borax 162 

Boron 116 

Boyle's law 23 

Bright line spectra 43 

Brimstone 118 

British gum 310 

Bromine 140 

Bromoform 272 

Brucine 356 

Burned 'lime 175 

Butyric acid 287 

C. 

Cadaverine 360 

Cadmium 223 



452 



INDEX 



Caffeine 357 

Calcium 174 

carbide 178 

carbonate 175 

chloride 174 

hydroxide 175 

hypochlorite 177 

nitrate 176 

oxide 175 

phosphate 177 

sulphate 176 

superphosphate 177 

Calomel 218 

Caloric 21 

Calorie 32 

great 3 2 

Camphor, monobromated 332 

mint 332 

Camphors 332 

Cane-sugar 305 

Caoutchouc 331 

Capillary attraction 9 

depression 9 

Caproic acid 288 

Caprylic acid 288 

Carbinol 275 

Carbohydrates 259-301 

classification of 301 

tests for 311 

Carbolic acid 333 

tests for 311 

Carbonic acid 318 

Carbamide 416 

Carbon 109 

bisulphide 120 

compounds 241 

dioxide 113 

monoxide 112 

Carbylamines 325 

Carron oil 3 00 

Caseinogen 406 

Catalytic action 81 

Cathartic acid . 315 

Cathode 54 

Cause of Magnetism 56 

Cellulose 309 

dinitro 309 

group, the 309 

Cerebros 304 

Cerium oxalate - 300-188 

Charles, law of 29 

Chemical action, conditions in- 
fluencing 80 



Chemical action, distinction 

from physical.... 63-64 
laws governing . . 65, 66, 67 

prediction of 80 

arithmetic 74~75 

combination by weight, law 

of 66 

reaction 82 

symbols and equations 

72, 73, 74, 75 

Chemistry, definition of 1 

Chloral 280 

hydrate 281 

Chloride of lime 177 

Chlorides of urine 413 

estimation of 413 

Chlorinated lime 177 

Chlorine 134 

dioxide 140 

water 136 

Chloroform 271 

test for presence 272 

purity 272 

Cholesterin 402 

Chromate of potassium 200 

Chromic acid 200 

anhydride 199 

Chromium 198 

hydroxide 199 

ores 198 

oxide 199 

tests for 201 

trioxide 199 

Chromo-proteids 368 

Chyme , 397 

Cinchona bark 354 

Cinchonidine 355 

Cinchonine 355 

Circular polarization 47 

Cinnabar 221 

Citrate of bismuth 294 

iron 294 

and ammonium... 294 

lithium 294 

potassium 294 

Citric acid 293 

tests for 294 

Classification by reaction 80 

chemical composition. 84 

Mendelejeff's .. -. 86-87 

Classification of compounds... 83 

elements 85 



INDEX 



453 



Coal 265 

oil 266 

Coal-tar camphor 345 

Cobalt 201 

chloride 201 

nitrate 201 

Cocaine 356 

Codeine 353 

Cohesion 8 

Colocynthin 315 

Colloids 11 

Color 39 

Compound ethers 259-295 

Compounds, definition of 64 

Composition of the body 382 

Compressibility 3 

Condensed benzene nuclei 344 

Conduction of heat 31 

Conine 352 

Constancy of composition, law 

of 66 

Constitutional formula 247 

Constitution of gases, physical. 20 

Convection of heat 31 

Copper 209 

Copper, acetate of 287 

Copper, ammonio compounds. . 210 

carbonate 210 

chloride 210 

oxides 210 

sulphate 210 

tests for 211 

toxicology of 211 

Creosote 333 

Critical temperature 36 

Crith 70 

Crystalloids 11 

Cupric acetate 287 

Cuprum T 209 

Cyanic acid 324 

Cyanide of mercury 322 

potassium 322 

silver 322 

Cyanogen 320-259 

Cymene 330 

D. 

Davy's safety lamp 112 

Decimal system 14 

Deliquescence 98 

Density 15 

Dentine 393 



Depression, capillary 9 

Derivative 251 

Derived albuminoids 369 

Destructive distillation 38 

Dextrin 310 

Dextrose 304 

Diacetic acid in urine 431 

test for 431 

Dialysis 11 

Dialyzer 11 

Diamine 104 

Diazo-reaction 430 

Diazo and azo-compounds. .259-343 
Diethylsulphonyl - methyl-ethyl- 
methane 281 

Diffusion 9 

of liquids 10 

of gases 10 

Digestion 394 

intestinal 400 

mouth 394 

stomach 395 

Digitalein 315 

Digitalin 315 

Digitonin 315 

Digitoxin 315 

Dimethyl benzene 330 

ketone 282 

Dimethyl - diethylsulphonyl- 

methane 281 

Dinitro-benzene 340 

Dinitro-cellulose 309 

Diphenyl-amine 341 

Disaccharids 305 

Dispersion of light 41 

Distillation 37 

destructive 38 

fractional 38 

Distilled water 97 

Divisibility 3 

Donovan's solution 225 

Double salt 85 

Dried alum 187 

Drinking water 97 

Drying oils 299 

Ductility 5 

Dynamical theory of heat 24 

E. 

Efflorescence 98 

Elasticity, or tension 23 

Electricity 51 



454 



INDEX 



Electricity by chemical action. 53 

by friction 52 

by magnetic induction. . . 55-57 

negative or resinous 51 

positive or vitreous 51 

Electric battery 53 

Electrical units 60-61 

Electromagnets 56 

Electromagnetism 55 

Electrolysis 59 

Elements, definition of 65 

Elements, the 85 

Empirical formula 246 

Enamel 393 

Energy 7 

kinetic 7 

potential 7 

English system of weights and 

measures 14 

Enzymes 256 

•Equation 74 

Erythrocytes 389 

Eserine 357 

Esters 295 

Ethene or ethylene 268 

Ethers 259-295 

Ether, acetic 297 

compound spirit of 297 

ethyl 296 

methyl 296 

methyl-ethyl 297 

spirit of 297 

waves 38 

Ethyl acetate . . . . 297 

alcohol 275 

aldehyde 280 

chloride 271 

nitrite 297 

Eucalyptol 332 

Exalgin 342 

Examination of stomach con- 
tents 397 

Extension or figure 3 

F. 

Fats ' 298 

decomposition of 300 

occurrence in nature 299 

Fehling's test 31 1-427 

Fecal matter 403 

Fermentation 255 

test 312-428 

Ferments 256 



Ferricyanide of potassium 323 

Ferric acetate 286 

chloride 191 

citrate 294 

hydroxide 192 

hypophosphite 194 

nitrate 194 

oxide 192 

phosphate 194 

subsulphate solution 193 

sulphate 193 

Ferrocyanide of potassium.... 323 

test for albumen 424 

Ferrous bromide 191 

carbonate 194 

chloride 191 

ferric oxide 192 

hydroxide 192 

iodide 191 

lactate 290 

oxide 19 2 

phosphate 194 

sulphate 193 

sulphide 191 

Ferrum 189 

redactum 190 

Filtration 372 

Flame no 

structure no 

Fleitmann's test 229 

Flowers of sulphur 118 

Fluorescence 44 

Fluorine 145 

Food, animal 383 

utilization of 385 

Formaldehyde 279 

Formamide 318 

Formic acid 285 

aldehyde 279 

Formula, a 73 

empirical 246 

graphic 246 

molecular 246 

Formula, percentage . . . 246 

Fractional distillation 38 

Frauenhofer lines 44 

French system of weights and 

measures 14 

Fusel oil 2.77 

G. 

Galactose " 304 

Gallic acid 337 



INDEX 



455 



Gallon 14 

Imperial 14 

Gas, illuminating 267 

volume and atomic weight. 71 

Gases, correction of volume. 29-30 

elasticity or tension of . . . 23 

expansion of 29 

molecular constitution of 

68, 69, 70 

physical constitution of . . . 20 

Gastric juice 395 

Gay-Lussac, law of 67 

Glucosides, definition of 260 

Globulins 367 

Glucose 304 

Glucosides 314 

Glycerin 278 

Glycocol 318 

Glycogen 308 

Glycocholate of sodium 403 

Glycocholic acid 403 

Glycolic acid 289 

Glyceryl trinitrate 298 

Gmelin's test for bile 429 

Gold 235 

chloride 237 

tests for 2^,7 

Gram, the 15 

Grape-sugar 304 

Graphic formula 247 

types 249 

Gravimetric analysis 371 

Gravitation 11 

terrestrial 12 

Gravity, center of 12 

Great calorie 32 

Guaiacol 334 

Gum arabic 310 

Gum-resins 331 

Gums 310 

Gun-cotton, soluble 309 

Gutta percha 331 

Gypsum 176 

Gutzeit's test 228 

H. 

Hair, horns, hoofs, &c 394 

Haines' test , 427 

Halogens 133 

Hardness 6 

Hard rubber 331 

Heat 24 



Heat, conduction of 31 

convection of 31 

definition of 24 

dynamical theory of 24 

expansion by 24 

of liquids 25 

of solids 24 

of water 25 

latent .. . 33-36 

physical effects 24 

radiation of 32 

test for albumin 423 

transmission of 30 

specific 32-33 

waves 38 

Heating and lighting effects of 

electricity 58 

Hematin 390 

Hemin 390 

Hemochromagen 340 

Hemoglobin 390 

Heintz's method for uric acid. . 421 

Hippuric acid 422 

Hoffmann's anodyne 297 

Homologous series 251 

Human milk 407 

Hydrargyrum 216 

Hydrazine 104 

Hydrazines 259-343 

Hydrocarbons, acetylene series. 269 

aromatic 326 

classification 262 

definition 258-260 

halogen derivatives 270 

olefine series 267 

paraffine series 262 

Hydrocyanic acid 321 

Hydrogen 91-94 

chloride' 136 

iodide 144 

monoxide 97 

peroxide 99 

persulphide 120 

phosphide 129 

sulphide 119 

Hydrometers 19 

Hydrosulphide of ammonium.. 167 

Hydrous body 98 

Hydroxide 98 

Hygroscopism 98 

Hyoscine 357 

Hyoscyamine 356 

Hypochlorous oxide 138 



456 



INDEX 



I. 

Ichthyol 334 

Ignition, temperature of 1 1 1 

Illuminating gas 267 

oil 266 

Imperial gallon 14 

pint 14 

Indestructibility 5 

India rubber 331 

Indican 422 

tests for 423 

Indicators 375 

definition of 84 

Indoxyl potassium sulphate.... 422 

Inertia 5 

Inosite 305 

Intestinal digestion 400 

juice 402 

Iodine 142 

solution 352 

Iodoform 272 

Iodol 349 

Iron 189 

and ammonium citrate.... 294 

and ammonium tartrate. . . 292 

by hydrogen 190 

carbonate 194 

chlorides 19 1 

dialyzed . 194 

hydrated oxide 192 

hydroxide 192 

hypophosphite 194 

iodide 19 2 

magnetic ore 19 2 

nitrate 194 

ores 189 

oxide 192 

phosphates 194 

pig 190 

potassium tartrate 292 

reduced 190 

sulphides 191 

wrought 190 

Isologous series 252 

Isomerism 252 

Iso-sulphocyanate of allyl 324 

Iso-sulphocyanates 324 

J. 

Juice, gastric 394 

intestinal 402 



K. 

Ketone, dimethyl 282 

Ketones 258-282 

Kinetic energy 7 

L. 

Lactate of iron 290 

strontium . 290 

Lactic acid 290 

Lactose 306 

Latent heat 33-36 

Law of Avogadro 69 

Law of Charles 29 

chemical combination by 

volume 67 

constancy of composition. 66 

Boyle (or Mariotte) 23 

multiple proportions 66 

Ohm's 61 

Laws of Berthollet 81 

Lead 206 

acetate 287 

carbonate 207 

iodide 208 

nitrate 207 

oxide 207 

sulphate 208 

tests for 209 

toxicology of 208 

Length, measures of 14 

Leucocytes 391 

Leucomaines 260-360 

creatinine group 361 

uric acid group 361 

Levulose 305 

Light 38 

direction of 40 

dispersion of 41 

nature of 38 

reflection of 40 

refraction of 40 

theories of 38 

Liebermann's reaction 366 

Lignine 309 

Lime water 173 

Liniment of ammonia 300 

lime 300 

Lines, Frauenhofer 44 

Line, vertical 12 

Linking power of atoms 249 

Linoleic acid : 289 

Liquefaction 33 






INDEX 



457 



Liter, the 15 

Litharge . .' 207 

Lithium 163 

bromide and carbonate.... 163 

citrate 294 

Load-stone 50 

Lymph 392 

M. 

Mercuric iodide 220 

oxide 220 

sulphate 221 

sulphide 221 

Mercurous chloride 218 

nitrate 221 

iodide 219 

oxide 220 

sulphate 221 

Mercury 216 

ores 216 

poison by 223 

preparation of 217 

properties of 217 

tests for 222 

yellow subsulphate 221 

Melitose 307 

Menthol 332 

Metals 149 

alkali 151 

alkaline earths 173 

classification of 150 

definition of 85 

earth 184 

general properties 149 

magnesium group 170 

Metals of the arsenic group... 224 

lead group 206 

iron group 188 

preparation of 150 

Meta-di-hydroxy-benzene 334 

Metameric bodies 252 

Meta-phenyl-diamine 341 

Meter, the 14 

Methyl acetanilide 342 

aldehyde 279 

benzene 329 

chloride 271 

ether 296 

ethyl ether 297 

salicylate 337 

Method of Raoult 79 

Magnesium 170 

carbonate - 171 



Magnesium chloride 171 

citrate, effervescent solu- 
tion 295 

hydroxide . . . 171 

oxide 171 

phosphate 172 

sulphate 1 72 

Magnet 50 

Magnetism 50 

cause of 56 

electricity produced by. . . . 57 

Malleability 6 

Malic acid 291 

Maltose , 205 

Malt-sugar 306 

Manganate of potassium 197 

Manganese 195 

chlorides 197 

oxides 196 

sulphates 197 

Manganic acid 197 

anhydride 197 

Mannose 304 

Margaric acid 288 

Mariott and Boyle, law of.... 23 

Marsh's test 229 

Matter, definition of 2 

general properties of ... . 2 

specific properties of 2 

Mayer's reagent 351 

Measures of length 14 

Meconic acid 353 

Mendelejeff's classification. . .86-87 

table 90 

Meniscus 8 

Mercaptans 281 

Mercuric ammonium chloride. . 222 

chloride 219 

cyanide 322 

nitrate 221 

Methods of determining atomic 

weights 76-77 

molecular weights . . 78-79 

quantitative analysis. 371 

Metric system weights and 

measures 14 

Millon's reagent 366 

Mineral waters 92 

Mint camphor 332 

Milk 405 

fat 407 

sugar 406 

Modification, allotropic 85 



458 



INDEX 



Molecular constitution of gases 
68, 69, 70 

formula 246 

Molecules 4-68 

in gases 5 

in liquids 4 

in solid bodies 4 

Molybdenum 238 

Monobromated camphor 332 

Monosaccharids 303 

Monsel's solution 193 

Morphine 353 

Mouth digestion 394 

Murexid test 421 

Muscarine 360 

Muscle 392 

sugar 305 

Mutual action of electric cur- 
rents 56 

Myronic acid 3 X 6 

N. 

Naphthalene 345 

Naphthol 346 

Native albuminoids 368 

Natrium 158 

Natural fats 298 

gas 266 

Nascent state 82 

Negative electricity . . 5 1 

Neurine 360 

Neutral bodies, definition of... 84 

Neutralization equivalents .... 377 

Nicotine 352 

Nitrogen 100 

dioxide 105 

monoxide 105 

pentoxide 106 

trioxide 106 

Nitrogenous organic bodies.... 3 l( > 

Nitroglycerin • 298 

Nitro-benzene 379 

Nitro-compounds 3 2 5 

Nitro-derivatives of benzene.. 338 

Nitrous ether 297 

Nitric acid test for albumin. . . 424 

Nitrils 324 

Nitrite of amyl 298 

Nomenclature 82-83 

Non-drying oils 299 

Non-metals, definition of 85 

general properties ... 91 

Normal constituents of urine.. 413 



Normal salt 84 

solutions .' 374 

Nucleo-proteids 368 

O. 

Official alum 186 

Ohm's law 60 

Ohm, the 60 

Oil, coal 266 

fusel 2T] 

illuminating 266 

mineral 266 

of bitter almonds. ........ 334 

of vitriol 122 

Oils, drying 299 

non-drying 299 

Olefine series 267 

Olein 298 

Oleic acid 288 

Oleoresins 331 

Osmosis 11 

Opacity 6 

Opium 352 

deodorized 352 

Optical axis 46 

Organic acids 258-283 

definition of 242 

bodies, action of heat upon 254 
action of nitric acid 

upon 254 

action of oxygen upon. 254 

chemical changes in.. 253 

classification of 258 

general properties of. 252 

chemistry 241 

compounds, analysis of . . . 243 

elements forming 242 

separation and purifi- 
cation 243 

source 243 

Organized bodies 242 

ferments 256 

Oxalate of cerium 291 

Oxalic acid 291-422 

Oxybenzoic acid 33^ 

Oxygen 94~96 

1 acids of bromine 142 

iodine 145 

Ozone 96 

P. 

Paraformaldehyde 279 

Palmitic acid 288 



INDEX 



459 



Palmitin 298 

Paraffine 267 

series 262 

Paraldehyde 280 

elixir 280 

Pelargonic acid 288 

Pentene 268 

Percentage formula 246 

Permanganic acid 197 

anhydride 197 

Petroleum 266 

Pettenkofer's test 430 

Phenol 333 

acids 336 

phthalein 336 

sulphonic acid 334 

Phenols 333 

Phenomena 2 

Phloridzin 315 

Phosphates of urine 414 

estimation of 415 

Phosphoretted hydrogen 129 

Phosphoric oxide 130 

Phosphorus 126 

amorphous 127 

oxide 127 

poisoning by 128 

Phthalic acid 335 

Physical constitution of gases. 20 

Physics 7 

Physiological chemistry 379 

definition 380 

introduction 379 

Pigments, bile 402 

Pint 14 

Imperial 14 

Platinum 237 

black 238 

perchloride 238 

/ tests 238 

Plant fibre 309 

Plasma 389 

Plaques, blood 392 

Polariscope 48 

Polarization 44 

circular 47 

by reflection 45 

refraction 45 

Polymeric bodies 252 

Polysaccharids 307 

Poisonous proteids 361 

Porcelain 187 

Porosity 3 



Positive electricity 51 

Potassa sulphurata 157 

Potassium 151 

acetate 286 

and antimony tartrate .... 292 

bicarbonate 155 

bichromate 200 

bitartrate 292 

bromide 155 

carbonate 155 

chlorate 157 

chloride 154 

chromate 200 

citrate 294 

cyanide 322 

ferricyanide . 323 

ferrocyanide 323 

hydroxide 153 

hypophosphite 157 

iodide 154 

manganate 197 

nitrate 155 

oxide 153 

permanganate 198 

sodium tartrate 292 

sulphate 156 

Potential energy 7 

Precipitated sulphur 118 

Prediction of chemical reaction. 80 

Pressure, atmospheric 21 

Proteoses and peptones 368 

Proteids 361 

action of acids and alka- 
lies on 365 

action of heat 365 

action of oxidizing agents. 365 

chromo 368 

classification of 366 

composition 364 

definition 260 

general properties 364 

nucleo 368 

occurrence in nature 363 

Proteids, tests for 365 

Ptomaines 260-357 

physical properties of 359 

properties of 358 

Ptyalin 395 

Pump, air 22 

Pus in urine 426 

Putrefaction 255-257 

Pyridine 347 

bases 259-347 



460 



INDEX 



Pyrogallic acid 334 

Pyrogallol 334 

Pyroxylin 309 

Pyrrole 349 

derivatives 259 

Q. 

Quantitative analysis 371 

of stomach contents.. 399 

Quantivalence 71-72 

Quick-lime 175 

Quicksilver 216 

Quinidine 355 

Quinine 354 

bisulphate 354 

sulphate 354 

tests 355 

R. 

Radiation of heat 3 2 

Radical 82-251 

Radium 181 

Reaction, chemical 82 

prediction of 80 

Reagent 82 

Red blood corpuscles 389 

Red oxide of mercury 220 

Reduced iron 190 

Reflection of light 40 

Refraction of light 40 

Reinsch's test 229 

Rennin 396 

Resins 33 1 

Resorcin 334 

Resorcinol 334 

Respiration 403 

Robert's test for albumen 424 

Roll sulphur 118 

Rotatory power, specific 49 

Rubber, hard 33 * 

India 331 

vulcanized 33 * 

S. 

Saccharids 301 

Saccharine 344 

Saccharose 305 

Saccharoses 305 

Saccharum, sucrose, sugar .... 305 

Saccharum lactis 306 

Safety lamp, Davy's 112 

Sal ammoniac 165 



Salicylate of methyl 2>Z7 

phenyl 337 

Salicylic acid 336 

Salicin 315 

Salt, acid or bi 84 

basic 84 

definition of 84 

double 84 

normal . . 84 

Selenium 125 

Series, homologous 251 

isologous 252 

Silicates, aluminum 187 

Silicon 115 

Silver 214 

chemically pure 215 

chloride 215 

cyanide 322 

iodide 216 

nitrate 215 

oxide 215 

poisoning by 216 

tests for 216 

Soap 300 

green 300 

soft 300 

Sodium 158 

acetate 286 

arsenate 227 

bicarbonate 161 

borate 162 

bromide, iodide, chlorate.. 159 

cobaltic nitrite 202 

carbonate 160 

chloride 159 

dioxide 159 

glycocholate 403 

hydroxide 159 

hypochlorite 163 

hypophosphite 163 

nitrate 162 

orthophosphates 162 

oxide 159 

phosphate 162 

potassium tartrate 292 

sulphate 160 

sulphite 1 60 

taurocholate 403 

thiosulphate 160 

Solanin 316 

Solar spectrum, chemical rays. 49 

heat rays 49 

Soluble ferments 256 



INDEX 



46I 



Solutions, normal 374 

Sozalic acid 334 

Spartene 352 

Specific gravity 15 

methods of determin- 
ing 16 

in gases 20 

in liquids. ... 16 

in solids .... 17 

Specific heat 3 2 ~33 

Specific rotatory power 49 

Spectra absorption 43 

bright line 43 

Spectroscope 42 

Spectrum, continuous 43 

solar 49 

Spirit of Ether 297 

compound 297 

mindereris 286 

nitrous ether 298 

Sprengel's air-pump 22 

Stoechiometry 75 

Standard solutions 374 

Stannic chloride 235 

Stannous chloride 235 

Stannum 235 

Starch '. 307 

State, nascent 82 

Stearic acid 288 

Stearin 298 

Stearoptenes 332 

Stomach contents, examination 

of 397 

quantitative tests .... 399 

digestion 395 

Strophanthin 316 

Strontium 178 

bromide 179 

hydroxide 179 

iodide 179 

lactate 290 

oxide 179 

Stychnine 355 

tests 355 

Structural formula 247 

Structure of flame no 

Sublimation 37 

Substitution 251 

Sugar in urine 426 

quantitative estimation 428 

tests for 427 

Sulphanilic acid 342 

Sulphates of urine 415 



Sulphates of urine, estimation 

of 416 

Sulphocarbolate of sodium 324 

Sulphocarbolic acid 324 

Sulphocyanic acid 324 

Sulphonal 281 

Sulphur 117 

dioxide 121 

hydride 119 

trioxide 122 

varieties of 118 

Sweet spirit of nitre 298 

Symbol 73 

Systems of weights and meas- 
ures 14 

the decimal 14 

the English 14 

the French 14 

T. 
Table of metric weights and 

measures 15 

Tannic acid 338 

Tannin 338 

Tartar 391 

Tartaric acid 291 

Tartrate of iron and ammonium 292 
Tartrate of iron and potassium 292 
Tartrate of sodium and potas- 
sium 292 

Taurocholate of sodium 403 

Taurocholic acid 403 

Teeth 393 

Tellurium 125 

Temperature, absolute 29 

Temperature, critical 36 

of ignition in 

Tenacity . 5 

Tension 23 

Terebene 331 

Terpenes 330 

Tests for carbohydrates 312 

Tetronal 282 

Tetanine 360 

Theobromine 357 

Theorem of Archimedes 17 

Thermal unit 32 

Thermometer, the 2d 

construction of 26 

conversion of readings.... 28 

scale 27 

Thymol 352 

Tin 235 



462 



INDEX 



Titer 376 

Titration 376 

direct method 376 

indirect method 376 

residual method 376 

Toluene 329 

Toxalbumins 361 

Toxins 362 

Translucency 6 

Transmission of heat 30 

Transparency 6 

Tricalcium phosphate 177 

Trichlor-aldehyde 280 

Trichlor-methane 271 

Tri-bromo-methane 2"]2 

Tri-nitro-phenol 340 

Trional 281 

Tri-iodo-methane 2^2 

Trioxy-benzoic acid 337 

Trommer's test 311 

Turpentine, oil of 330 

Typhotoxine 360 

Tyrotoxicon 360 

U. 

Unit, thermal 32 

Urea 416 

estimation of 418 

Uric acid . 420 

detection of 421 

estimation of 421 

Urinary concretions 431 

analysis of 432 

rudiments 433 

chemical 434 

histological 440 

Urine, abnormal constituents of 423 

acetone in 430 

albumin in 423 

bile in 429 

blood in 425 

composition of 418 

diacetic acid in 431 

diazo-reaction 430 

normal constituents of.... 413 

properties of 4°9 

pus in 426 

sugar in 426 

the 407 

total solids of 4" 

Utilization of food 385 

V. 
Valerianic acid 287 



Valence 71-72 

Vertical line 12 

Vibrations, ether 38 

Vital force 241 

Vitriol, oil of 122 

Volatilization 34 

Volt, the 61 

Volume of gases, correction of. 30 

Volumetric analysis 374 

Vulcanized rubber 331 

W. 

Wagner's reagent 352 

Washed sulphur 118 

Washing soda 160 

Water 97 

mineral 97 

of crystallization 98 

Waves, ether 38 

Waxes 299 

Weight 12 

atomic 70-71 

Weights and measures 14 

the English 14 

the French or decimal .... 14 

White blood corpuscles 391 

precipitate 222 

Wine or fluid measure 14 

Wood naphtha 274 

spirit 274 

X. 
Xylene 330 

Y. 

Yellow oxide of mercury 220 

subsulphate of mercury... 221 

Z. 

Zero, absolute 29 

Zinc 202 

acetate 286 

bromide 203 

carbonate 204 

chloride 203 

hydroxide 203 

iodide 204 

oxide 203 

phosphide 204 

sulphate 204 

tests for 204 



N 



